tracing: Enable creating new instance early boot

[linux-2.6-microblaze.git] / kernel / trace / trace.h

// SPDX-License-Identifier: GPL-2.0

#ifndef _LINUX_KERNEL_TRACE_H
#define _LINUX_KERNEL_TRACE_H

#include <linux/fs.h>
#include <linux/atomic.h>
#include <linux/sched.h>
#include <linux/clocksource.h>
#include <linux/ring_buffer.h>
#include <linux/mmiotrace.h>
#include <linux/tracepoint.h>
#include <linux/ftrace.h>
#include <linux/trace.h>
#include <linux/hw_breakpoint.h>
#include <linux/trace_seq.h>
#include <linux/trace_events.h>
#include <linux/compiler.h>
#include <linux/glob.h>
#include <linux/irq_work.h>
#include <linux/workqueue.h>

#ifdef CONFIG_FTRACE_SYSCALLS
#include <asm/unistd.h>         /* For NR_SYSCALLS           */
#include <asm/syscall.h>        /* some archs define it here */
#endif

enum trace_type {
        __TRACE_FIRST_TYPE = 0,

        TRACE_FN,
        TRACE_CTX,
        TRACE_WAKE,
        TRACE_STACK,
        TRACE_PRINT,
        TRACE_BPRINT,
        TRACE_MMIO_RW,
        TRACE_MMIO_MAP,
        TRACE_BRANCH,
        TRACE_GRAPH_RET,
        TRACE_GRAPH_ENT,
        TRACE_USER_STACK,
        TRACE_BLK,
        TRACE_BPUTS,
        TRACE_HWLAT,
        TRACE_RAW_DATA,

        __TRACE_LAST_TYPE,
};


#undef __field
#define __field(type, item)             type    item;

#undef __field_fn
#define __field_fn(type, item)          type    item;

#undef __field_struct
#define __field_struct(type, item)      __field(type, item)

#undef __field_desc
#define __field_desc(type, container, item)

#undef __field_packed
#define __field_packed(type, container, item)

#undef __array
#define __array(type, item, size)       type    item[size];

#undef __array_desc
#define __array_desc(type, container, item, size)

#undef __dynamic_array
#define __dynamic_array(type, item)     type    item[];

#undef F_STRUCT
#define F_STRUCT(args...)               args

#undef FTRACE_ENTRY
#define FTRACE_ENTRY(name, struct_name, id, tstruct, print)             \
        struct struct_name {                                            \
                struct trace_entry      ent;                            \
                tstruct                                                 \
        }

#undef FTRACE_ENTRY_DUP
#define FTRACE_ENTRY_DUP(name, name_struct, id, tstruct, printk)

#undef FTRACE_ENTRY_REG
#define FTRACE_ENTRY_REG(name, struct_name, id, tstruct, print, regfn)  \
        FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print))

#undef FTRACE_ENTRY_PACKED
#define FTRACE_ENTRY_PACKED(name, struct_name, id, tstruct, print)      \
        FTRACE_ENTRY(name, struct_name, id, PARAMS(tstruct), PARAMS(print)) __packed

#include "trace_entries.h"

/* Use this for memory failure errors */
#define MEM_FAIL(condition, fmt, ...) ({                        \
        static bool __section(.data.once) __warned;             \
        int __ret_warn_once = !!(condition);                    \
                                                                \
        if (unlikely(__ret_warn_once && !__warned)) {           \
                __warned = true;                                \
                pr_err("ERROR: " fmt, ##__VA_ARGS__);           \
        }                                                       \
        unlikely(__ret_warn_once);                              \
})

/*
 * syscalls are special, and need special handling, this is why
 * they are not included in trace_entries.h
 */
struct syscall_trace_enter {
        struct trace_entry      ent;
        int                     nr;
        unsigned long           args[];
};

struct syscall_trace_exit {
        struct trace_entry      ent;
        int                     nr;
        long                    ret;
};

struct kprobe_trace_entry_head {
        struct trace_entry      ent;
        unsigned long           ip;
};

struct kretprobe_trace_entry_head {
        struct trace_entry      ent;
        unsigned long           func;
        unsigned long           ret_ip;
};

/*
 * trace_flag_type is an enumeration that holds different
 * states when a trace occurs. These are:
 *  IRQS_OFF            - interrupts were disabled
 *  IRQS_NOSUPPORT      - arch does not support irqs_disabled_flags
 *  NEED_RESCHED        - reschedule is requested
 *  HARDIRQ             - inside an interrupt handler
 *  SOFTIRQ             - inside a softirq handler
 */
enum trace_flag_type {
        TRACE_FLAG_IRQS_OFF             = 0x01,
        TRACE_FLAG_IRQS_NOSUPPORT       = 0x02,
        TRACE_FLAG_NEED_RESCHED         = 0x04,
        TRACE_FLAG_HARDIRQ              = 0x08,
        TRACE_FLAG_SOFTIRQ              = 0x10,
        TRACE_FLAG_PREEMPT_RESCHED      = 0x20,
        TRACE_FLAG_NMI                  = 0x40,
};

#define TRACE_BUF_SIZE          1024

struct trace_array;

/*
 * The CPU trace array - it consists of thousands of trace entries
 * plus some other descriptor data: (for example which task started
 * the trace, etc.)
 */
struct trace_array_cpu {
        atomic_t                disabled;
        void                    *buffer_page;   /* ring buffer spare */

        unsigned long           entries;
        unsigned long           saved_latency;
        unsigned long           critical_start;
        unsigned long           critical_end;
        unsigned long           critical_sequence;
        unsigned long           nice;
        unsigned long           policy;
        unsigned long           rt_priority;
        unsigned long           skipped_entries;
        u64                     preempt_timestamp;
        pid_t                   pid;
        kuid_t                  uid;
        char                    comm[TASK_COMM_LEN];

#ifdef CONFIG_FUNCTION_TRACER
        int                     ftrace_ignore_pid;
#endif
        bool                    ignore_pid;
};

struct tracer;
struct trace_option_dentry;

struct array_buffer {
        struct trace_array              *tr;
        struct trace_buffer             *buffer;
        struct trace_array_cpu __percpu *data;
        u64                             time_start;
        int                             cpu;
};

#define TRACE_FLAGS_MAX_SIZE            32

struct trace_options {
        struct tracer                   *tracer;
        struct trace_option_dentry      *topts;
};

struct trace_pid_list {
        int                             pid_max;
        unsigned long                   *pids;
};

enum {
        TRACE_PIDS              = BIT(0),
        TRACE_NO_PIDS           = BIT(1),
};

static inline bool pid_type_enabled(int type, struct trace_pid_list *pid_list,
                                    struct trace_pid_list *no_pid_list)
{
        /* Return true if the pid list in type has pids */
        return ((type & TRACE_PIDS) && pid_list) ||
                ((type & TRACE_NO_PIDS) && no_pid_list);
}

static inline bool still_need_pid_events(int type, struct trace_pid_list *pid_list,
                                         struct trace_pid_list *no_pid_list)
{
        /*
         * Turning off what is in @type, return true if the "other"
         * pid list, still has pids in it.
         */
        return (!(type & TRACE_PIDS) && pid_list) ||
                (!(type & TRACE_NO_PIDS) && no_pid_list);
}

typedef bool (*cond_update_fn_t)(struct trace_array *tr, void *cond_data);

/**
 * struct cond_snapshot - conditional snapshot data and callback
 *
 * The cond_snapshot structure encapsulates a callback function and
 * data associated with the snapshot for a given tracing instance.
 *
 * When a snapshot is taken conditionally, by invoking
 * tracing_snapshot_cond(tr, cond_data), the cond_data passed in is
 * passed in turn to the cond_snapshot.update() function.  That data
 * can be compared by the update() implementation with the cond_data
 * contained wihin the struct cond_snapshot instance associated with
 * the trace_array.  Because the tr->max_lock is held throughout the
 * update() call, the update() function can directly retrieve the
 * cond_snapshot and cond_data associated with the per-instance
 * snapshot associated with the trace_array.
 *
 * The cond_snapshot.update() implementation can save data to be
 * associated with the snapshot if it decides to, and returns 'true'
 * in that case, or it returns 'false' if the conditional snapshot
 * shouldn't be taken.
 *
 * The cond_snapshot instance is created and associated with the
 * user-defined cond_data by tracing_cond_snapshot_enable().
 * Likewise, the cond_snapshot instance is destroyed and is no longer
 * associated with the trace instance by
 * tracing_cond_snapshot_disable().
 *
 * The method below is required.
 *
 * @update: When a conditional snapshot is invoked, the update()
 *      callback function is invoked with the tr->max_lock held.  The
 *      update() implementation signals whether or not to actually
 *      take the snapshot, by returning 'true' if so, 'false' if no
 *      snapshot should be taken.  Because the max_lock is held for
 *      the duration of update(), the implementation is safe to
 *      directly retrieven and save any implementation data it needs
 *      to in association with the snapshot.
 */
struct cond_snapshot {
        void                            *cond_data;
        cond_update_fn_t                update;
};

/*
 * The trace array - an array of per-CPU trace arrays. This is the
 * highest level data structure that individual tracers deal with.
 * They have on/off state as well:
 */
struct trace_array {
        struct list_head        list;
        char                    *name;
        struct array_buffer     array_buffer;
#ifdef CONFIG_TRACER_MAX_TRACE
        /*
         * The max_buffer is used to snapshot the trace when a maximum
         * latency is reached, or when the user initiates a snapshot.
         * Some tracers will use this to store a maximum trace while
         * it continues examining live traces.
         *
         * The buffers for the max_buffer are set up the same as the array_buffer
         * When a snapshot is taken, the buffer of the max_buffer is swapped
         * with the buffer of the array_buffer and the buffers are reset for
         * the array_buffer so the tracing can continue.
         */
        struct array_buffer     max_buffer;
        bool                    allocated_snapshot;
#endif
#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
        unsigned long           max_latency;
#ifdef CONFIG_FSNOTIFY
        struct dentry           *d_max_latency;
        struct work_struct      fsnotify_work;
        struct irq_work         fsnotify_irqwork;
#endif
#endif
        struct trace_pid_list   __rcu *filtered_pids;
        struct trace_pid_list   __rcu *filtered_no_pids;
        /*
         * max_lock is used to protect the swapping of buffers
         * when taking a max snapshot. The buffers themselves are
         * protected by per_cpu spinlocks. But the action of the swap
         * needs its own lock.
         *
         * This is defined as a arch_spinlock_t in order to help
         * with performance when lockdep debugging is enabled.
         *
         * It is also used in other places outside the update_max_tr
         * so it needs to be defined outside of the
         * CONFIG_TRACER_MAX_TRACE.
         */
        arch_spinlock_t         max_lock;
        int                     buffer_disabled;
#ifdef CONFIG_FTRACE_SYSCALLS
        int                     sys_refcount_enter;
        int                     sys_refcount_exit;
        struct trace_event_file __rcu *enter_syscall_files[NR_syscalls];
        struct trace_event_file __rcu *exit_syscall_files[NR_syscalls];
#endif
        int                     stop_count;
        int                     clock_id;
        int                     nr_topts;
        bool                    clear_trace;
        int                     buffer_percent;
        unsigned int            n_err_log_entries;
        struct tracer           *current_trace;
        unsigned int            trace_flags;
        unsigned char           trace_flags_index[TRACE_FLAGS_MAX_SIZE];
        unsigned int            flags;
        raw_spinlock_t          start_lock;
        struct list_head        err_log;
        struct dentry           *dir;
        struct dentry           *options;
        struct dentry           *percpu_dir;
        struct dentry           *event_dir;
        struct trace_options    *topts;
        struct list_head        systems;
        struct list_head        events;
        struct trace_event_file *trace_marker_file;
        cpumask_var_t           tracing_cpumask; /* only trace on set CPUs */
        int                     ref;
        int                     trace_ref;
#ifdef CONFIG_FUNCTION_TRACER
        struct ftrace_ops       *ops;
        struct trace_pid_list   __rcu *function_pids;
        struct trace_pid_list   __rcu *function_no_pids;
#ifdef CONFIG_DYNAMIC_FTRACE
        /* All of these are protected by the ftrace_lock */
        struct list_head        func_probes;
        struct list_head        mod_trace;
        struct list_head        mod_notrace;
#endif
        /* function tracing enabled */
        int                     function_enabled;
#endif
        int                     time_stamp_abs_ref;
        struct list_head        hist_vars;
#ifdef CONFIG_TRACER_SNAPSHOT
        struct cond_snapshot    *cond_snapshot;
#endif
};

enum {
        TRACE_ARRAY_FL_GLOBAL   = (1 << 0)
};

extern struct list_head ftrace_trace_arrays;

extern struct mutex trace_types_lock;

extern int trace_array_get(struct trace_array *tr);
extern int tracing_check_open_get_tr(struct trace_array *tr);
extern struct trace_array *trace_array_find(const char *instance);
extern struct trace_array *trace_array_find_get(const char *instance);

extern int tracing_set_time_stamp_abs(struct trace_array *tr, bool abs);
extern int tracing_set_clock(struct trace_array *tr, const char *clockstr);

extern bool trace_clock_in_ns(struct trace_array *tr);

/*
 * The global tracer (top) should be the first trace array added,
 * but we check the flag anyway.
 */
static inline struct trace_array *top_trace_array(void)
{
        struct trace_array *tr;

        if (list_empty(&ftrace_trace_arrays))
                return NULL;

        tr = list_entry(ftrace_trace_arrays.prev,
                        typeof(*tr), list);
        WARN_ON(!(tr->flags & TRACE_ARRAY_FL_GLOBAL));
        return tr;
}

#define FTRACE_CMP_TYPE(var, type) \
        __builtin_types_compatible_p(typeof(var), type *)

#undef IF_ASSIGN
#define IF_ASSIGN(var, entry, etype, id)                        \
        if (FTRACE_CMP_TYPE(var, etype)) {                      \
                var = (typeof(var))(entry);                     \
                WARN_ON(id != 0 && (entry)->type != id);        \
                break;                                          \
        }

/* Will cause compile errors if type is not found. */
extern void __ftrace_bad_type(void);

/*
 * The trace_assign_type is a verifier that the entry type is
 * the same as the type being assigned. To add new types simply
 * add a line with the following format:
 *
 * IF_ASSIGN(var, ent, type, id);
 *
 *  Where "type" is the trace type that includes the trace_entry
 *  as the "ent" item. And "id" is the trace identifier that is
 *  used in the trace_type enum.
 *
 *  If the type can have more than one id, then use zero.
 */
#define trace_assign_type(var, ent)                                     \
        do {                                                            \
                IF_ASSIGN(var, ent, struct ftrace_entry, TRACE_FN);     \
                IF_ASSIGN(var, ent, struct ctx_switch_entry, 0);        \
                IF_ASSIGN(var, ent, struct stack_entry, TRACE_STACK);   \
                IF_ASSIGN(var, ent, struct userstack_entry, TRACE_USER_STACK);\
                IF_ASSIGN(var, ent, struct print_entry, TRACE_PRINT);   \
                IF_ASSIGN(var, ent, struct bprint_entry, TRACE_BPRINT); \
                IF_ASSIGN(var, ent, struct bputs_entry, TRACE_BPUTS);   \
                IF_ASSIGN(var, ent, struct hwlat_entry, TRACE_HWLAT);   \
                IF_ASSIGN(var, ent, struct raw_data_entry, TRACE_RAW_DATA);\
                IF_ASSIGN(var, ent, struct trace_mmiotrace_rw,          \
                          TRACE_MMIO_RW);                               \
                IF_ASSIGN(var, ent, struct trace_mmiotrace_map,         \
                          TRACE_MMIO_MAP);                              \
                IF_ASSIGN(var, ent, struct trace_branch, TRACE_BRANCH); \
                IF_ASSIGN(var, ent, struct ftrace_graph_ent_entry,      \
                          TRACE_GRAPH_ENT);             \
                IF_ASSIGN(var, ent, struct ftrace_graph_ret_entry,      \
                          TRACE_GRAPH_RET);             \
                __ftrace_bad_type();                                    \
        } while (0)

/*
 * An option specific to a tracer. This is a boolean value.
 * The bit is the bit index that sets its value on the
 * flags value in struct tracer_flags.
 */
struct tracer_opt {
        const char      *name; /* Will appear on the trace_options file */
        u32             bit; /* Mask assigned in val field in tracer_flags */
};

/*
 * The set of specific options for a tracer. Your tracer
 * have to set the initial value of the flags val.
 */
struct tracer_flags {
        u32                     val;
        struct tracer_opt       *opts;
        struct tracer           *trace;
};

/* Makes more easy to define a tracer opt */
#define TRACER_OPT(s, b)        .name = #s, .bit = b


struct trace_option_dentry {
        struct tracer_opt               *opt;
        struct tracer_flags             *flags;
        struct trace_array              *tr;
        struct dentry                   *entry;
};

/**
 * struct tracer - a specific tracer and its callbacks to interact with tracefs
 * @name: the name chosen to select it on the available_tracers file
 * @init: called when one switches to this tracer (echo name > current_tracer)
 * @reset: called when one switches to another tracer
 * @start: called when tracing is unpaused (echo 1 > tracing_on)
 * @stop: called when tracing is paused (echo 0 > tracing_on)
 * @update_thresh: called when tracing_thresh is updated
 * @open: called when the trace file is opened
 * @pipe_open: called when the trace_pipe file is opened
 * @close: called when the trace file is released
 * @pipe_close: called when the trace_pipe file is released
 * @read: override the default read callback on trace_pipe
 * @splice_read: override the default splice_read callback on trace_pipe
 * @selftest: selftest to run on boot (see trace_selftest.c)
 * @print_headers: override the first lines that describe your columns
 * @print_line: callback that prints a trace
 * @set_flag: signals one of your private flags changed (trace_options file)
 * @flags: your private flags
 */
struct tracer {
        const char              *name;
        int                     (*init)(struct trace_array *tr);
        void                    (*reset)(struct trace_array *tr);
        void                    (*start)(struct trace_array *tr);
        void                    (*stop)(struct trace_array *tr);
        int                     (*update_thresh)(struct trace_array *tr);
        void                    (*open)(struct trace_iterator *iter);
        void                    (*pipe_open)(struct trace_iterator *iter);
        void                    (*close)(struct trace_iterator *iter);
        void                    (*pipe_close)(struct trace_iterator *iter);
        ssize_t                 (*read)(struct trace_iterator *iter,
                                        struct file *filp, char __user *ubuf,
                                        size_t cnt, loff_t *ppos);
        ssize_t                 (*splice_read)(struct trace_iterator *iter,
                                               struct file *filp,
                                               loff_t *ppos,
                                               struct pipe_inode_info *pipe,
                                               size_t len,
                                               unsigned int flags);
#ifdef CONFIG_FTRACE_STARTUP_TEST
        int                     (*selftest)(struct tracer *trace,
                                            struct trace_array *tr);
#endif
        void                    (*print_header)(struct seq_file *m);
        enum print_line_t       (*print_line)(struct trace_iterator *iter);
        /* If you handled the flag setting, return 0 */
        int                     (*set_flag)(struct trace_array *tr,
                                            u32 old_flags, u32 bit, int set);
        /* Return 0 if OK with change, else return non-zero */
        int                     (*flag_changed)(struct trace_array *tr,
                                                u32 mask, int set);
        struct tracer           *next;
        struct tracer_flags     *flags;
        int                     enabled;
        bool                    print_max;
        bool                    allow_instances;
#ifdef CONFIG_TRACER_MAX_TRACE
        bool                    use_max_tr;
#endif
        /* True if tracer cannot be enabled in kernel param */
        bool                    noboot;
};


/* Only current can touch trace_recursion */

/*
 * For function tracing recursion:
 *  The order of these bits are important.
 *
 *  When function tracing occurs, the following steps are made:
 *   If arch does not support a ftrace feature:
 *    call internal function (uses INTERNAL bits) which calls...
 *   If callback is registered to the "global" list, the list
 *    function is called and recursion checks the GLOBAL bits.
 *    then this function calls...
 *   The function callback, which can use the FTRACE bits to
 *    check for recursion.
 *
 * Now if the arch does not suppport a feature, and it calls
 * the global list function which calls the ftrace callback
 * all three of these steps will do a recursion protection.
 * There's no reason to do one if the previous caller already
 * did. The recursion that we are protecting against will
 * go through the same steps again.
 *
 * To prevent the multiple recursion checks, if a recursion
 * bit is set that is higher than the MAX bit of the current
 * check, then we know that the check was made by the previous
 * caller, and we can skip the current check.
 */
enum {
        /* Function recursion bits */
        TRACE_FTRACE_BIT,
        TRACE_FTRACE_NMI_BIT,
        TRACE_FTRACE_IRQ_BIT,
        TRACE_FTRACE_SIRQ_BIT,

        /* INTERNAL_BITs must be greater than FTRACE_BITs */
        TRACE_INTERNAL_BIT,
        TRACE_INTERNAL_NMI_BIT,
        TRACE_INTERNAL_IRQ_BIT,
        TRACE_INTERNAL_SIRQ_BIT,

        TRACE_BRANCH_BIT,
/*
 * Abuse of the trace_recursion.
 * As we need a way to maintain state if we are tracing the function
 * graph in irq because we want to trace a particular function that
 * was called in irq context but we have irq tracing off. Since this
 * can only be modified by current, we can reuse trace_recursion.
 */
        TRACE_IRQ_BIT,

        /* Set if the function is in the set_graph_function file */
        TRACE_GRAPH_BIT,

        /*
         * In the very unlikely case that an interrupt came in
         * at a start of graph tracing, and we want to trace
         * the function in that interrupt, the depth can be greater
         * than zero, because of the preempted start of a previous
         * trace. In an even more unlikely case, depth could be 2
         * if a softirq interrupted the start of graph tracing,
         * followed by an interrupt preempting a start of graph
         * tracing in the softirq, and depth can even be 3
         * if an NMI came in at the start of an interrupt function
         * that preempted a softirq start of a function that
         * preempted normal context!!!! Luckily, it can't be
         * greater than 3, so the next two bits are a mask
         * of what the depth is when we set TRACE_GRAPH_BIT
         */

        TRACE_GRAPH_DEPTH_START_BIT,
        TRACE_GRAPH_DEPTH_END_BIT,

        /*
         * To implement set_graph_notrace, if this bit is set, we ignore
         * function graph tracing of called functions, until the return
         * function is called to clear it.
         */
        TRACE_GRAPH_NOTRACE_BIT,
};

#define trace_recursion_set(bit)        do { (current)->trace_recursion |= (1<<(bit)); } while (0)
#define trace_recursion_clear(bit)      do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
#define trace_recursion_test(bit)       ((current)->trace_recursion & (1<<(bit)))

#define trace_recursion_depth() \
        (((current)->trace_recursion >> TRACE_GRAPH_DEPTH_START_BIT) & 3)
#define trace_recursion_set_depth(depth) \
        do {                                                            \
                current->trace_recursion &=                             \
                        ~(3 << TRACE_GRAPH_DEPTH_START_BIT);            \
                current->trace_recursion |=                             \
                        ((depth) & 3) << TRACE_GRAPH_DEPTH_START_BIT;   \
        } while (0)

#define TRACE_CONTEXT_BITS      4

#define TRACE_FTRACE_START      TRACE_FTRACE_BIT
#define TRACE_FTRACE_MAX        ((1 << (TRACE_FTRACE_START + TRACE_CONTEXT_BITS)) - 1)

#define TRACE_LIST_START        TRACE_INTERNAL_BIT
#define TRACE_LIST_MAX          ((1 << (TRACE_LIST_START + TRACE_CONTEXT_BITS)) - 1)

#define TRACE_CONTEXT_MASK      TRACE_LIST_MAX

static __always_inline int trace_get_context_bit(void)
{
        int bit;

        if (in_interrupt()) {
                if (in_nmi())
                        bit = 0;

                else if (in_irq())
                        bit = 1;
                else
                        bit = 2;
        } else
                bit = 3;

        return bit;
}

static __always_inline int trace_test_and_set_recursion(int start, int max)
{
        unsigned int val = current->trace_recursion;
        int bit;

        /* A previous recursion check was made */
        if ((val & TRACE_CONTEXT_MASK) > max)
                return 0;

        bit = trace_get_context_bit() + start;
        if (unlikely(val & (1 << bit)))
                return -1;

        val |= 1 << bit;
        current->trace_recursion = val;
        barrier();

        return bit;
}

static __always_inline void trace_clear_recursion(int bit)
{
        unsigned int val = current->trace_recursion;

        if (!bit)
                return;

        bit = 1 << bit;
        val &= ~bit;

        barrier();
        current->trace_recursion = val;
}

static inline struct ring_buffer_iter *
trace_buffer_iter(struct trace_iterator *iter, int cpu)
{
        return iter->buffer_iter ? iter->buffer_iter[cpu] : NULL;
}

int tracer_init(struct tracer *t, struct trace_array *tr);
int tracing_is_enabled(void);
void tracing_reset_online_cpus(struct array_buffer *buf);
void tracing_reset_current(int cpu);
void tracing_reset_all_online_cpus(void);
int tracing_open_generic(struct inode *inode, struct file *filp);
int tracing_open_generic_tr(struct inode *inode, struct file *filp);
bool tracing_is_disabled(void);
bool tracer_tracing_is_on(struct trace_array *tr);
void tracer_tracing_on(struct trace_array *tr);
void tracer_tracing_off(struct trace_array *tr);
struct dentry *trace_create_file(const char *name,
                                 umode_t mode,
                                 struct dentry *parent,
                                 void *data,
                                 const struct file_operations *fops);

int tracing_init_dentry(void);

struct ring_buffer_event;

struct ring_buffer_event *
trace_buffer_lock_reserve(struct trace_buffer *buffer,
                          int type,
                          unsigned long len,
                          unsigned long flags,
                          int pc);

struct trace_entry *tracing_get_trace_entry(struct trace_array *tr,
                                                struct trace_array_cpu *data);

struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,
                                          int *ent_cpu, u64 *ent_ts);

void trace_buffer_unlock_commit_nostack(struct trace_buffer *buffer,
                                        struct ring_buffer_event *event);

int trace_empty(struct trace_iterator *iter);

void *trace_find_next_entry_inc(struct trace_iterator *iter);

void trace_init_global_iter(struct trace_iterator *iter);

void tracing_iter_reset(struct trace_iterator *iter, int cpu);

unsigned long trace_total_entries_cpu(struct trace_array *tr, int cpu);
unsigned long trace_total_entries(struct trace_array *tr);

void trace_function(struct trace_array *tr,
                    unsigned long ip,
                    unsigned long parent_ip,
                    unsigned long flags, int pc);
void trace_graph_function(struct trace_array *tr,
                    unsigned long ip,
                    unsigned long parent_ip,
                    unsigned long flags, int pc);
void trace_latency_header(struct seq_file *m);
void trace_default_header(struct seq_file *m);
void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
int trace_empty(struct trace_iterator *iter);

void trace_graph_return(struct ftrace_graph_ret *trace);
int trace_graph_entry(struct ftrace_graph_ent *trace);
void set_graph_array(struct trace_array *tr);

void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
void tracing_start_tgid_record(void);
void tracing_stop_tgid_record(void);

int register_tracer(struct tracer *type);
int is_tracing_stopped(void);

loff_t tracing_lseek(struct file *file, loff_t offset, int whence);

extern cpumask_var_t __read_mostly tracing_buffer_mask;

#define for_each_tracing_cpu(cpu)       \
        for_each_cpu(cpu, tracing_buffer_mask)

extern unsigned long nsecs_to_usecs(unsigned long nsecs);

extern unsigned long tracing_thresh;

/* PID filtering */

extern int pid_max;

bool trace_find_filtered_pid(struct trace_pid_list *filtered_pids,
                             pid_t search_pid);
bool trace_ignore_this_task(struct trace_pid_list *filtered_pids,
                            struct trace_pid_list *filtered_no_pids,
                            struct task_struct *task);
void trace_filter_add_remove_task(struct trace_pid_list *pid_list,
                                  struct task_struct *self,
                                  struct task_struct *task);
void *trace_pid_next(struct trace_pid_list *pid_list, void *v, loff_t *pos);
void *trace_pid_start(struct trace_pid_list *pid_list, loff_t *pos);
int trace_pid_show(struct seq_file *m, void *v);
void trace_free_pid_list(struct trace_pid_list *pid_list);
int trace_pid_write(struct trace_pid_list *filtered_pids,
                    struct trace_pid_list **new_pid_list,
                    const char __user *ubuf, size_t cnt);

#ifdef CONFIG_TRACER_MAX_TRACE
void update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu,
                   void *cond_data);
void update_max_tr_single(struct trace_array *tr,
                          struct task_struct *tsk, int cpu);
#endif /* CONFIG_TRACER_MAX_TRACE */

#if (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
        defined(CONFIG_FSNOTIFY)

void latency_fsnotify(struct trace_array *tr);

#else

static inline void latency_fsnotify(struct trace_array *tr) { }

#endif

#ifdef CONFIG_STACKTRACE
void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
                   int pc);
#else
static inline void __trace_stack(struct trace_array *tr, unsigned long flags,
                                 int skip, int pc)
{
}
#endif /* CONFIG_STACKTRACE */

extern u64 ftrace_now(int cpu);

extern void trace_find_cmdline(int pid, char comm[]);
extern int trace_find_tgid(int pid);
extern void trace_event_follow_fork(struct trace_array *tr, bool enable);

#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_update_tot_cnt;
extern unsigned long ftrace_number_of_pages;
extern unsigned long ftrace_number_of_groups;
void ftrace_init_trace_array(struct trace_array *tr);
#else
static inline void ftrace_init_trace_array(struct trace_array *tr) { }
#endif
#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
extern int DYN_FTRACE_TEST_NAME(void);
#define DYN_FTRACE_TEST_NAME2 trace_selftest_dynamic_test_func2
extern int DYN_FTRACE_TEST_NAME2(void);

extern bool ring_buffer_expanded;
extern bool tracing_selftest_disabled;

#ifdef CONFIG_FTRACE_STARTUP_TEST
extern int trace_selftest_startup_function(struct tracer *trace,
                                           struct trace_array *tr);
extern int trace_selftest_startup_function_graph(struct tracer *trace,
                                                 struct trace_array *tr);
extern int trace_selftest_startup_irqsoff(struct tracer *trace,
                                          struct trace_array *tr);
extern int trace_selftest_startup_preemptoff(struct tracer *trace,
                                             struct trace_array *tr);
extern int trace_selftest_startup_preemptirqsoff(struct tracer *trace,
                                                 struct trace_array *tr);
extern int trace_selftest_startup_wakeup(struct tracer *trace,
                                         struct trace_array *tr);
extern int trace_selftest_startup_nop(struct tracer *trace,
                                         struct trace_array *tr);
extern int trace_selftest_startup_branch(struct tracer *trace,
                                         struct trace_array *tr);
/*
 * Tracer data references selftest functions that only occur
 * on boot up. These can be __init functions. Thus, when selftests
 * are enabled, then the tracers need to reference __init functions.
 */
#define __tracer_data           __refdata
#else
/* Tracers are seldom changed. Optimize when selftests are disabled. */
#define __tracer_data           __read_mostly
#endif /* CONFIG_FTRACE_STARTUP_TEST */

extern void *head_page(struct trace_array_cpu *data);
extern unsigned long long ns2usecs(u64 nsec);
extern int
trace_vbprintk(unsigned long ip, const char *fmt, va_list args);
extern int
trace_vprintk(unsigned long ip, const char *fmt, va_list args);
extern int
trace_array_vprintk(struct trace_array *tr,
                    unsigned long ip, const char *fmt, va_list args);
int trace_array_printk_buf(struct trace_buffer *buffer,
                           unsigned long ip, const char *fmt, ...);
void trace_printk_seq(struct trace_seq *s);
enum print_line_t print_trace_line(struct trace_iterator *iter);

extern char trace_find_mark(unsigned long long duration);

struct ftrace_hash;

struct ftrace_mod_load {
        struct list_head        list;
        char                    *func;
        char                    *module;
        int                      enable;
};

enum {
        FTRACE_HASH_FL_MOD      = (1 << 0),
};

struct ftrace_hash {
        unsigned long           size_bits;
        struct hlist_head       *buckets;
        unsigned long           count;
        unsigned long           flags;
        struct rcu_head         rcu;
};

struct ftrace_func_entry *
ftrace_lookup_ip(struct ftrace_hash *hash, unsigned long ip);

static __always_inline bool ftrace_hash_empty(struct ftrace_hash *hash)
{
        return !hash || !(hash->count || (hash->flags & FTRACE_HASH_FL_MOD));
}

/* Standard output formatting function used for function return traces */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER

/* Flag options */
#define TRACE_GRAPH_PRINT_OVERRUN       0x1
#define TRACE_GRAPH_PRINT_CPU           0x2
#define TRACE_GRAPH_PRINT_OVERHEAD      0x4
#define TRACE_GRAPH_PRINT_PROC          0x8
#define TRACE_GRAPH_PRINT_DURATION      0x10
#define TRACE_GRAPH_PRINT_ABS_TIME      0x20
#define TRACE_GRAPH_PRINT_REL_TIME      0x40
#define TRACE_GRAPH_PRINT_IRQS          0x80
#define TRACE_GRAPH_PRINT_TAIL          0x100
#define TRACE_GRAPH_SLEEP_TIME          0x200
#define TRACE_GRAPH_GRAPH_TIME          0x400
#define TRACE_GRAPH_PRINT_FILL_SHIFT    28
#define TRACE_GRAPH_PRINT_FILL_MASK     (0x3 << TRACE_GRAPH_PRINT_FILL_SHIFT)

extern void ftrace_graph_sleep_time_control(bool enable);

#ifdef CONFIG_FUNCTION_PROFILER
extern void ftrace_graph_graph_time_control(bool enable);
#else
static inline void ftrace_graph_graph_time_control(bool enable) { }
#endif

extern enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags);
extern void print_graph_headers_flags(struct seq_file *s, u32 flags);
extern void
trace_print_graph_duration(unsigned long long duration, struct trace_seq *s);
extern void graph_trace_open(struct trace_iterator *iter);
extern void graph_trace_close(struct trace_iterator *iter);
extern int __trace_graph_entry(struct trace_array *tr,
                               struct ftrace_graph_ent *trace,
                               unsigned long flags, int pc);
extern void __trace_graph_return(struct trace_array *tr,
                                 struct ftrace_graph_ret *trace,
                                 unsigned long flags, int pc);

#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;

static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
        unsigned long addr = trace->func;
        int ret = 0;
        struct ftrace_hash *hash;

        preempt_disable_notrace();

        /*
         * Have to open code "rcu_dereference_sched()" because the
         * function graph tracer can be called when RCU is not
         * "watching".
         * Protected with schedule_on_each_cpu(ftrace_sync)
         */
        hash = rcu_dereference_protected(ftrace_graph_hash, !preemptible());

        if (ftrace_hash_empty(hash)) {
                ret = 1;
                goto out;
        }

        if (ftrace_lookup_ip(hash, addr)) {

                /*
                 * This needs to be cleared on the return functions
                 * when the depth is zero.
                 */
                trace_recursion_set(TRACE_GRAPH_BIT);
                trace_recursion_set_depth(trace->depth);

                /*
                 * If no irqs are to be traced, but a set_graph_function
                 * is set, and called by an interrupt handler, we still
                 * want to trace it.
                 */
                if (in_irq())
                        trace_recursion_set(TRACE_IRQ_BIT);
                else
                        trace_recursion_clear(TRACE_IRQ_BIT);
                ret = 1;
        }

out:
        preempt_enable_notrace();
        return ret;
}

static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
{
        if (trace_recursion_test(TRACE_GRAPH_BIT) &&
            trace->depth == trace_recursion_depth())
                trace_recursion_clear(TRACE_GRAPH_BIT);
}

static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
        int ret = 0;
        struct ftrace_hash *notrace_hash;

        preempt_disable_notrace();

        /*
         * Have to open code "rcu_dereference_sched()" because the
         * function graph tracer can be called when RCU is not
         * "watching".
         * Protected with schedule_on_each_cpu(ftrace_sync)
         */
        notrace_hash = rcu_dereference_protected(ftrace_graph_notrace_hash,
                                                 !preemptible());

        if (ftrace_lookup_ip(notrace_hash, addr))
                ret = 1;

        preempt_enable_notrace();
        return ret;
}
#else
static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
        return 1;
}

static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
        return 0;
}
static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
{ }
#endif /* CONFIG_DYNAMIC_FTRACE */

extern unsigned int fgraph_max_depth;

static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
{
        /* trace it when it is-nested-in or is a function enabled. */
        return !(trace_recursion_test(TRACE_GRAPH_BIT) ||
                 ftrace_graph_addr(trace)) ||
                (trace->depth < 0) ||
                (fgraph_max_depth && trace->depth >= fgraph_max_depth);
}

#else /* CONFIG_FUNCTION_GRAPH_TRACER */
static inline enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
        return TRACE_TYPE_UNHANDLED;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

extern struct list_head ftrace_pids;

#ifdef CONFIG_FUNCTION_TRACER

#define FTRACE_PID_IGNORE       -1
#define FTRACE_PID_TRACE        -2

struct ftrace_func_command {
        struct list_head        list;
        char                    *name;
        int                     (*func)(struct trace_array *tr,
                                        struct ftrace_hash *hash,
                                        char *func, char *cmd,
                                        char *params, int enable);
};
extern bool ftrace_filter_param __initdata;
static inline int ftrace_trace_task(struct trace_array *tr)
{
        return this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid) !=
                FTRACE_PID_IGNORE;
}
extern int ftrace_is_dead(void);
int ftrace_create_function_files(struct trace_array *tr,
                                 struct dentry *parent);
void ftrace_destroy_function_files(struct trace_array *tr);
int ftrace_allocate_ftrace_ops(struct trace_array *tr);
void ftrace_free_ftrace_ops(struct trace_array *tr);
void ftrace_init_global_array_ops(struct trace_array *tr);
void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func);
void ftrace_reset_array_ops(struct trace_array *tr);
void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer);
void ftrace_init_tracefs_toplevel(struct trace_array *tr,
                                  struct dentry *d_tracer);
void ftrace_clear_pids(struct trace_array *tr);
int init_function_trace(void);
void ftrace_pid_follow_fork(struct trace_array *tr, bool enable);
#else
static inline int ftrace_trace_task(struct trace_array *tr)
{
        return 1;
}
static inline int ftrace_is_dead(void) { return 0; }
static inline int
ftrace_create_function_files(struct trace_array *tr,
                             struct dentry *parent)
{
        return 0;
}
static inline int ftrace_allocate_ftrace_ops(struct trace_array *tr)
{
        return 0;
}
static inline void ftrace_free_ftrace_ops(struct trace_array *tr) { }
static inline void ftrace_destroy_function_files(struct trace_array *tr) { }
static inline __init void
ftrace_init_global_array_ops(struct trace_array *tr) { }
static inline void ftrace_reset_array_ops(struct trace_array *tr) { }
static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }
static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }
static inline void ftrace_clear_pids(struct trace_array *tr) { }
static inline int init_function_trace(void) { return 0; }
static inline void ftrace_pid_follow_fork(struct trace_array *tr, bool enable) { }
/* ftace_func_t type is not defined, use macro instead of static inline */
#define ftrace_init_array_ops(tr, func) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER */

#if defined(CONFIG_FUNCTION_TRACER) && defined(CONFIG_DYNAMIC_FTRACE)

struct ftrace_probe_ops {
        void                    (*func)(unsigned long ip,
                                        unsigned long parent_ip,
                                        struct trace_array *tr,
                                        struct ftrace_probe_ops *ops,
                                        void *data);
        int                     (*init)(struct ftrace_probe_ops *ops,
                                        struct trace_array *tr,
                                        unsigned long ip, void *init_data,
                                        void **data);
        void                    (*free)(struct ftrace_probe_ops *ops,
                                        struct trace_array *tr,
                                        unsigned long ip, void *data);
        int                     (*print)(struct seq_file *m,
                                         unsigned long ip,
                                         struct ftrace_probe_ops *ops,
                                         void *data);
};

struct ftrace_func_mapper;
typedef int (*ftrace_mapper_func)(void *data);

struct ftrace_func_mapper *allocate_ftrace_func_mapper(void);
void **ftrace_func_mapper_find_ip(struct ftrace_func_mapper *mapper,
                                           unsigned long ip);
int ftrace_func_mapper_add_ip(struct ftrace_func_mapper *mapper,
                               unsigned long ip, void *data);
void *ftrace_func_mapper_remove_ip(struct ftrace_func_mapper *mapper,
                                   unsigned long ip);
void free_ftrace_func_mapper(struct ftrace_func_mapper *mapper,
                             ftrace_mapper_func free_func);

extern int
register_ftrace_function_probe(char *glob, struct trace_array *tr,
                               struct ftrace_probe_ops *ops, void *data);
extern int
unregister_ftrace_function_probe_func(char *glob, struct trace_array *tr,
                                      struct ftrace_probe_ops *ops);
extern void clear_ftrace_function_probes(struct trace_array *tr);

int register_ftrace_command(struct ftrace_func_command *cmd);
int unregister_ftrace_command(struct ftrace_func_command *cmd);

void ftrace_create_filter_files(struct ftrace_ops *ops,
                                struct dentry *parent);
void ftrace_destroy_filter_files(struct ftrace_ops *ops);

extern int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
                             int len, int reset);
extern int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
                              int len, int reset);
#else
struct ftrace_func_command;

static inline __init int register_ftrace_command(struct ftrace_func_command *cmd)
{
        return -EINVAL;
}
static inline __init int unregister_ftrace_command(char *cmd_name)
{
        return -EINVAL;
}
static inline void clear_ftrace_function_probes(struct trace_array *tr)
{
}

/*
 * The ops parameter passed in is usually undefined.
 * This must be a macro.
 */
#define ftrace_create_filter_files(ops, parent) do { } while (0)
#define ftrace_destroy_filter_files(ops) do { } while (0)
#endif /* CONFIG_FUNCTION_TRACER && CONFIG_DYNAMIC_FTRACE */

bool ftrace_event_is_function(struct trace_event_call *call);

/*
 * struct trace_parser - servers for reading the user input separated by spaces
 * @cont: set if the input is not complete - no final space char was found
 * @buffer: holds the parsed user input
 * @idx: user input length
 * @size: buffer size
 */
struct trace_parser {
        bool            cont;
        char            *buffer;
        unsigned        idx;
        unsigned        size;
};

static inline bool trace_parser_loaded(struct trace_parser *parser)
{
        return (parser->idx != 0);
}

static inline bool trace_parser_cont(struct trace_parser *parser)
{
        return parser->cont;
}

static inline void trace_parser_clear(struct trace_parser *parser)
{
        parser->cont = false;
        parser->idx = 0;
}

extern int trace_parser_get_init(struct trace_parser *parser, int size);
extern void trace_parser_put(struct trace_parser *parser);
extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf,
        size_t cnt, loff_t *ppos);

/*
 * Only create function graph options if function graph is configured.
 */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
# define FGRAPH_FLAGS                                           \
                C(DISPLAY_GRAPH,        "display-graph"),
#else
# define FGRAPH_FLAGS
#endif

#ifdef CONFIG_BRANCH_TRACER
# define BRANCH_FLAGS                                   \
                C(BRANCH,               "branch"),
#else
# define BRANCH_FLAGS
#endif

#ifdef CONFIG_FUNCTION_TRACER
# define FUNCTION_FLAGS                                         \
                C(FUNCTION,             "function-trace"),      \
                C(FUNC_FORK,            "function-fork"),
# define FUNCTION_DEFAULT_FLAGS         TRACE_ITER_FUNCTION
#else
# define FUNCTION_FLAGS
# define FUNCTION_DEFAULT_FLAGS         0UL
# define TRACE_ITER_FUNC_FORK           0UL
#endif

#ifdef CONFIG_STACKTRACE
# define STACK_FLAGS                            \
                C(STACKTRACE,           "stacktrace"),
#else
# define STACK_FLAGS
#endif

/*
 * trace_iterator_flags is an enumeration that defines bit
 * positions into trace_flags that controls the output.
 *
 * NOTE: These bits must match the trace_options array in
 *       trace.c (this macro guarantees it).
 */
#define TRACE_FLAGS                                             \
                C(PRINT_PARENT,         "print-parent"),        \
                C(SYM_OFFSET,           "sym-offset"),          \
                C(SYM_ADDR,             "sym-addr"),            \
                C(VERBOSE,              "verbose"),             \
                C(RAW,                  "raw"),                 \
                C(HEX,                  "hex"),                 \
                C(BIN,                  "bin"),                 \
                C(BLOCK,                "block"),               \
                C(PRINTK,               "trace_printk"),        \
                C(ANNOTATE,             "annotate"),            \
                C(USERSTACKTRACE,       "userstacktrace"),      \
                C(SYM_USEROBJ,          "sym-userobj"),         \
                C(PRINTK_MSGONLY,       "printk-msg-only"),     \
                C(CONTEXT_INFO,         "context-info"),   /* Print pid/cpu/time */ \
                C(LATENCY_FMT,          "latency-format"),      \
                C(RECORD_CMD,           "record-cmd"),          \
                C(RECORD_TGID,          "record-tgid"),         \
                C(OVERWRITE,            "overwrite"),           \
                C(STOP_ON_FREE,         "disable_on_free"),     \
                C(IRQ_INFO,             "irq-info"),            \
                C(MARKERS,              "markers"),             \
                C(EVENT_FORK,           "event-fork"),          \
                C(PAUSE_ON_TRACE,       "pause-on-trace"),      \
                FUNCTION_FLAGS                                  \
                FGRAPH_FLAGS                                    \
                STACK_FLAGS                                     \
                BRANCH_FLAGS

/*
 * By defining C, we can make TRACE_FLAGS a list of bit names
 * that will define the bits for the flag masks.
 */
#undef C
#define C(a, b) TRACE_ITER_##a##_BIT

enum trace_iterator_bits {
        TRACE_FLAGS
        /* Make sure we don't go more than we have bits for */
        TRACE_ITER_LAST_BIT
};

/*
 * By redefining C, we can make TRACE_FLAGS a list of masks that
 * use the bits as defined above.
 */
#undef C
#define C(a, b) TRACE_ITER_##a = (1 << TRACE_ITER_##a##_BIT)

enum trace_iterator_flags { TRACE_FLAGS };

/*
 * TRACE_ITER_SYM_MASK masks the options in trace_flags that
 * control the output of kernel symbols.
 */
#define TRACE_ITER_SYM_MASK \
        (TRACE_ITER_PRINT_PARENT|TRACE_ITER_SYM_OFFSET|TRACE_ITER_SYM_ADDR)

extern struct tracer nop_trace;

#ifdef CONFIG_BRANCH_TRACER
extern int enable_branch_tracing(struct trace_array *tr);
extern void disable_branch_tracing(void);
static inline int trace_branch_enable(struct trace_array *tr)
{
        if (tr->trace_flags & TRACE_ITER_BRANCH)
                return enable_branch_tracing(tr);
        return 0;
}
static inline void trace_branch_disable(void)
{
        /* due to races, always disable */
        disable_branch_tracing();
}
#else
static inline int trace_branch_enable(struct trace_array *tr)
{
        return 0;
}
static inline void trace_branch_disable(void)
{
}
#endif /* CONFIG_BRANCH_TRACER */

/* set ring buffers to default size if not already done so */
int tracing_update_buffers(void);

struct ftrace_event_field {
        struct list_head        link;
        const char              *name;
        const char              *type;
        int                     filter_type;
        int                     offset;
        int                     size;
        int                     is_signed;
};

struct prog_entry;

struct event_filter {
        struct prog_entry __rcu *prog;
        char                    *filter_string;
};

struct event_subsystem {
        struct list_head        list;
        const char              *name;
        struct event_filter     *filter;
        int                     ref_count;
};

struct trace_subsystem_dir {
        struct list_head                list;
        struct event_subsystem          *subsystem;
        struct trace_array              *tr;
        struct dentry                   *entry;
        int                             ref_count;
        int                             nr_events;
};

extern int call_filter_check_discard(struct trace_event_call *call, void *rec,
                                     struct trace_buffer *buffer,
                                     struct ring_buffer_event *event);

void trace_buffer_unlock_commit_regs(struct trace_array *tr,
                                     struct trace_buffer *buffer,
                                     struct ring_buffer_event *event,
                                     unsigned long flags, int pc,
                                     struct pt_regs *regs);

static inline void trace_buffer_unlock_commit(struct trace_array *tr,
                                              struct trace_buffer *buffer,
                                              struct ring_buffer_event *event,
                                              unsigned long flags, int pc)
{
        trace_buffer_unlock_commit_regs(tr, buffer, event, flags, pc, NULL);
}

DECLARE_PER_CPU(struct ring_buffer_event *, trace_buffered_event);
DECLARE_PER_CPU(int, trace_buffered_event_cnt);
void trace_buffered_event_disable(void);
void trace_buffered_event_enable(void);

static inline void
__trace_event_discard_commit(struct trace_buffer *buffer,
                             struct ring_buffer_event *event)
{
        if (this_cpu_read(trace_buffered_event) == event) {
                /* Simply release the temp buffer */
                this_cpu_dec(trace_buffered_event_cnt);
                return;
        }
        ring_buffer_discard_commit(buffer, event);
}

/*
 * Helper function for event_trigger_unlock_commit{_regs}().
 * If there are event triggers attached to this event that requires
 * filtering against its fields, then they wil be called as the
 * entry already holds the field information of the current event.
 *
 * It also checks if the event should be discarded or not.
 * It is to be discarded if the event is soft disabled and the
 * event was only recorded to process triggers, or if the event
 * filter is active and this event did not match the filters.
 *
 * Returns true if the event is discarded, false otherwise.
 */
static inline bool
__event_trigger_test_discard(struct trace_event_file *file,
                             struct trace_buffer *buffer,
                             struct ring_buffer_event *event,
                             void *entry,
                             enum event_trigger_type *tt)
{
        unsigned long eflags = file->flags;

        if (eflags & EVENT_FILE_FL_TRIGGER_COND)
                *tt = event_triggers_call(file, entry, event);

        if (test_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &file->flags) ||
            (unlikely(file->flags & EVENT_FILE_FL_FILTERED) &&
             !filter_match_preds(file->filter, entry))) {
                __trace_event_discard_commit(buffer, event);
                return true;
        }

        return false;
}

/**
 * event_trigger_unlock_commit - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 */
static inline void
event_trigger_unlock_commit(struct trace_event_file *file,
                            struct trace_buffer *buffer,
                            struct ring_buffer_event *event,
                            void *entry, unsigned long irq_flags, int pc)
{
        enum event_trigger_type tt = ETT_NONE;

        if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
                trace_buffer_unlock_commit(file->tr, buffer, event, irq_flags, pc);

        if (tt)
                event_triggers_post_call(file, tt);
}

/**
 * event_trigger_unlock_commit_regs - handle triggers and finish event commit
 * @file: The file pointer assoctiated to the event
 * @buffer: The ring buffer that the event is being written to
 * @event: The event meta data in the ring buffer
 * @entry: The event itself
 * @irq_flags: The state of the interrupts at the start of the event
 * @pc: The state of the preempt count at the start of the event.
 *
 * This is a helper function to handle triggers that require data
 * from the event itself. It also tests the event against filters and
 * if the event is soft disabled and should be discarded.
 *
 * Same as event_trigger_unlock_commit() but calls
 * trace_buffer_unlock_commit_regs() instead of trace_buffer_unlock_commit().
 */
static inline void
event_trigger_unlock_commit_regs(struct trace_event_file *file,
                                 struct trace_buffer *buffer,
                                 struct ring_buffer_event *event,
                                 void *entry, unsigned long irq_flags, int pc,
                                 struct pt_regs *regs)
{
        enum event_trigger_type tt = ETT_NONE;

        if (!__event_trigger_test_discard(file, buffer, event, entry, &tt))
                trace_buffer_unlock_commit_regs(file->tr, buffer, event,
                                                irq_flags, pc, regs);

        if (tt)
                event_triggers_post_call(file, tt);
}

#define FILTER_PRED_INVALID     ((unsigned short)-1)
#define FILTER_PRED_IS_RIGHT    (1 << 15)
#define FILTER_PRED_FOLD        (1 << 15)

/*
 * The max preds is the size of unsigned short with
 * two flags at the MSBs. One bit is used for both the IS_RIGHT
 * and FOLD flags. The other is reserved.
 *
 * 2^14 preds is way more than enough.
 */
#define MAX_FILTER_PRED         16384

struct filter_pred;
struct regex;

typedef int (*filter_pred_fn_t) (struct filter_pred *pred, void *event);

typedef int (*regex_match_func)(char *str, struct regex *r, int len);

enum regex_type {
        MATCH_FULL = 0,
        MATCH_FRONT_ONLY,
        MATCH_MIDDLE_ONLY,
        MATCH_END_ONLY,
        MATCH_GLOB,
        MATCH_INDEX,
};

struct regex {
        char                    pattern[MAX_FILTER_STR_VAL];
        int                     len;
        int                     field_len;
        regex_match_func        match;
};

struct filter_pred {
        filter_pred_fn_t        fn;
        u64                     val;
        struct regex            regex;
        unsigned short          *ops;
        struct ftrace_event_field *field;
        int                     offset;
        int                     not;
        int                     op;
};

static inline bool is_string_field(struct ftrace_event_field *field)
{
        return field->filter_type == FILTER_DYN_STRING ||
               field->filter_type == FILTER_STATIC_STRING ||
               field->filter_type == FILTER_PTR_STRING ||
               field->filter_type == FILTER_COMM;
}

static inline bool is_function_field(struct ftrace_event_field *field)
{
        return field->filter_type == FILTER_TRACE_FN;
}

extern enum regex_type
filter_parse_regex(char *buff, int len, char **search, int *not);
extern void print_event_filter(struct trace_event_file *file,
                               struct trace_seq *s);
extern int apply_event_filter(struct trace_event_file *file,
                              char *filter_string);
extern int apply_subsystem_event_filter(struct trace_subsystem_dir *dir,
                                        char *filter_string);
extern void print_subsystem_event_filter(struct event_subsystem *system,
                                         struct trace_seq *s);
extern int filter_assign_type(const char *type);
extern int create_event_filter(struct trace_array *tr,
                               struct trace_event_call *call,
                               char *filter_str, bool set_str,
                               struct event_filter **filterp);
extern void free_event_filter(struct event_filter *filter);

struct ftrace_event_field *
trace_find_event_field(struct trace_event_call *call, char *name);

extern void trace_event_enable_cmd_record(bool enable);
extern void trace_event_enable_tgid_record(bool enable);

extern int event_trace_init(void);
extern int event_trace_add_tracer(struct dentry *parent, struct trace_array *tr);
extern int event_trace_del_tracer(struct trace_array *tr);

extern struct trace_event_file *__find_event_file(struct trace_array *tr,
                                                  const char *system,
                                                  const char *event);
extern struct trace_event_file *find_event_file(struct trace_array *tr,
                                                const char *system,
                                                const char *event);

static inline void *event_file_data(struct file *filp)
{
        return READ_ONCE(file_inode(filp)->i_private);
}

extern struct mutex event_mutex;
extern struct list_head ftrace_events;

extern const struct file_operations event_trigger_fops;
extern const struct file_operations event_hist_fops;
extern const struct file_operations event_hist_debug_fops;
extern const struct file_operations event_inject_fops;

#ifdef CONFIG_HIST_TRIGGERS
extern int register_trigger_hist_cmd(void);
extern int register_trigger_hist_enable_disable_cmds(void);
#else
static inline int register_trigger_hist_cmd(void) { return 0; }
static inline int register_trigger_hist_enable_disable_cmds(void) { return 0; }
#endif

extern int register_trigger_cmds(void);
extern void clear_event_triggers(struct trace_array *tr);

struct event_trigger_data {
        unsigned long                   count;
        int                             ref;
        struct event_trigger_ops        *ops;
        struct event_command            *cmd_ops;
        struct event_filter __rcu       *filter;
        char                            *filter_str;
        void                            *private_data;
        bool                            paused;
        bool                            paused_tmp;
        struct list_head                list;
        char                            *name;
        struct list_head                named_list;
        struct event_trigger_data       *named_data;
};

/* Avoid typos */
#define ENABLE_EVENT_STR        "enable_event"
#define DISABLE_EVENT_STR       "disable_event"
#define ENABLE_HIST_STR         "enable_hist"
#define DISABLE_HIST_STR        "disable_hist"

struct enable_trigger_data {
        struct trace_event_file         *file;
        bool                            enable;
        bool                            hist;
};

extern int event_enable_trigger_print(struct seq_file *m,
                                      struct event_trigger_ops *ops,
                                      struct event_trigger_data *data);
extern void event_enable_trigger_free(struct event_trigger_ops *ops,
                                      struct event_trigger_data *data);
extern int event_enable_trigger_func(struct event_command *cmd_ops,
                                     struct trace_event_file *file,
                                     char *glob, char *cmd, char *param);
extern int event_enable_register_trigger(char *glob,
                                         struct event_trigger_ops *ops,
                                         struct event_trigger_data *data,
                                         struct trace_event_file *file);
extern void event_enable_unregister_trigger(char *glob,
                                            struct event_trigger_ops *ops,
                                            struct event_trigger_data *test,
                                            struct trace_event_file *file);
extern void trigger_data_free(struct event_trigger_data *data);
extern int event_trigger_init(struct event_trigger_ops *ops,
                              struct event_trigger_data *data);
extern int trace_event_trigger_enable_disable(struct trace_event_file *file,
                                              int trigger_enable);
extern void update_cond_flag(struct trace_event_file *file);
extern int set_trigger_filter(char *filter_str,
                              struct event_trigger_data *trigger_data,
                              struct trace_event_file *file);
extern struct event_trigger_data *find_named_trigger(const char *name);
extern bool is_named_trigger(struct event_trigger_data *test);
extern int save_named_trigger(const char *name,
                              struct event_trigger_data *data);
extern void del_named_trigger(struct event_trigger_data *data);
extern void pause_named_trigger(struct event_trigger_data *data);
extern void unpause_named_trigger(struct event_trigger_data *data);
extern void set_named_trigger_data(struct event_trigger_data *data,
                                   struct event_trigger_data *named_data);
extern struct event_trigger_data *
get_named_trigger_data(struct event_trigger_data *data);
extern int register_event_command(struct event_command *cmd);
extern int unregister_event_command(struct event_command *cmd);
extern int register_trigger_hist_enable_disable_cmds(void);

/**
 * struct event_trigger_ops - callbacks for trace event triggers
 *
 * The methods in this structure provide per-event trigger hooks for
 * various trigger operations.
 *
 * All the methods below, except for @init() and @free(), must be
 * implemented.
 *
 * @func: The trigger 'probe' function called when the triggering
 *      event occurs.  The data passed into this callback is the data
 *      that was supplied to the event_command @reg() function that
 *      registered the trigger (see struct event_command) along with
 *      the trace record, rec.
 *
 * @init: An optional initialization function called for the trigger
 *      when the trigger is registered (via the event_command reg()
 *      function).  This can be used to perform per-trigger
 *      initialization such as incrementing a per-trigger reference
 *      count, for instance.  This is usually implemented by the
 *      generic utility function @event_trigger_init() (see
 *      trace_event_triggers.c).
 *
 * @free: An optional de-initialization function called for the
 *      trigger when the trigger is unregistered (via the
 *      event_command @reg() function).  This can be used to perform
 *      per-trigger de-initialization such as decrementing a
 *      per-trigger reference count and freeing corresponding trigger
 *      data, for instance.  This is usually implemented by the
 *      generic utility function @event_trigger_free() (see
 *      trace_event_triggers.c).
 *
 * @print: The callback function invoked to have the trigger print
 *      itself.  This is usually implemented by a wrapper function
 *      that calls the generic utility function @event_trigger_print()
 *      (see trace_event_triggers.c).
 */
struct event_trigger_ops {
        void                    (*func)(struct event_trigger_data *data,
                                        void *rec,
                                        struct ring_buffer_event *rbe);
        int                     (*init)(struct event_trigger_ops *ops,
                                        struct event_trigger_data *data);
        void                    (*free)(struct event_trigger_ops *ops,
                                        struct event_trigger_data *data);
        int                     (*print)(struct seq_file *m,
                                         struct event_trigger_ops *ops,
                                         struct event_trigger_data *data);
};

/**
 * struct event_command - callbacks and data members for event commands
 *
 * Event commands are invoked by users by writing the command name
 * into the 'trigger' file associated with a trace event.  The
 * parameters associated with a specific invocation of an event
 * command are used to create an event trigger instance, which is
 * added to the list of trigger instances associated with that trace
 * event.  When the event is hit, the set of triggers associated with
 * that event is invoked.
 *
 * The data members in this structure provide per-event command data
 * for various event commands.
 *
 * All the data members below, except for @post_trigger, must be set
 * for each event command.
 *
 * @name: The unique name that identifies the event command.  This is
 *      the name used when setting triggers via trigger files.
 *
 * @trigger_type: A unique id that identifies the event command
 *      'type'.  This value has two purposes, the first to ensure that
 *      only one trigger of the same type can be set at a given time
 *      for a particular event e.g. it doesn't make sense to have both
 *      a traceon and traceoff trigger attached to a single event at
 *      the same time, so traceon and traceoff have the same type
 *      though they have different names.  The @trigger_type value is
 *      also used as a bit value for deferring the actual trigger
 *      action until after the current event is finished.  Some
 *      commands need to do this if they themselves log to the trace
 *      buffer (see the @post_trigger() member below).  @trigger_type
 *      values are defined by adding new values to the trigger_type
 *      enum in include/linux/trace_events.h.
 *
 * @flags: See the enum event_command_flags below.
 *
 * All the methods below, except for @set_filter() and @unreg_all(),
 * must be implemented.
 *
 * @func: The callback function responsible for parsing and
 *      registering the trigger written to the 'trigger' file by the
 *      user.  It allocates the trigger instance and registers it with
 *      the appropriate trace event.  It makes use of the other
 *      event_command callback functions to orchestrate this, and is
 *      usually implemented by the generic utility function
 *      @event_trigger_callback() (see trace_event_triggers.c).
 *
 * @reg: Adds the trigger to the list of triggers associated with the
 *      event, and enables the event trigger itself, after
 *      initializing it (via the event_trigger_ops @init() function).
 *      This is also where commands can use the @trigger_type value to
 *      make the decision as to whether or not multiple instances of
 *      the trigger should be allowed.  This is usually implemented by
 *      the generic utility function @register_trigger() (see
 *      trace_event_triggers.c).
 *
 * @unreg: Removes the trigger from the list of triggers associated
 *      with the event, and disables the event trigger itself, after
 *      initializing it (via the event_trigger_ops @free() function).
 *      This is usually implemented by the generic utility function
 *      @unregister_trigger() (see trace_event_triggers.c).
 *
 * @unreg_all: An optional function called to remove all the triggers
 *      from the list of triggers associated with the event.  Called
 *      when a trigger file is opened in truncate mode.
 *
 * @set_filter: An optional function called to parse and set a filter
 *      for the trigger.  If no @set_filter() method is set for the
 *      event command, filters set by the user for the command will be
 *      ignored.  This is usually implemented by the generic utility
 *      function @set_trigger_filter() (see trace_event_triggers.c).
 *
 * @get_trigger_ops: The callback function invoked to retrieve the
 *      event_trigger_ops implementation associated with the command.
 */
struct event_command {
        struct list_head        list;
        char                    *name;
        enum event_trigger_type trigger_type;
        int                     flags;
        int                     (*func)(struct event_command *cmd_ops,
                                        struct trace_event_file *file,
                                        char *glob, char *cmd, char *params);
        int                     (*reg)(char *glob,
                                       struct event_trigger_ops *ops,
                                       struct event_trigger_data *data,
                                       struct trace_event_file *file);
        void                    (*unreg)(char *glob,
                                         struct event_trigger_ops *ops,
                                         struct event_trigger_data *data,
                                         struct trace_event_file *file);
        void                    (*unreg_all)(struct trace_event_file *file);
        int                     (*set_filter)(char *filter_str,
                                              struct event_trigger_data *data,
                                              struct trace_event_file *file);
        struct event_trigger_ops *(*get_trigger_ops)(char *cmd, char *param);
};

/**
 * enum event_command_flags - flags for struct event_command
 *
 * @POST_TRIGGER: A flag that says whether or not this command needs
 *      to have its action delayed until after the current event has
 *      been closed.  Some triggers need to avoid being invoked while
 *      an event is currently in the process of being logged, since
 *      the trigger may itself log data into the trace buffer.  Thus
 *      we make sure the current event is committed before invoking
 *      those triggers.  To do that, the trigger invocation is split
 *      in two - the first part checks the filter using the current
 *      trace record; if a command has the @post_trigger flag set, it
 *      sets a bit for itself in the return value, otherwise it
 *      directly invokes the trigger.  Once all commands have been
 *      either invoked or set their return flag, the current record is
 *      either committed or discarded.  At that point, if any commands
 *      have deferred their triggers, those commands are finally
 *      invoked following the close of the current event.  In other
 *      words, if the event_trigger_ops @func() probe implementation
 *      itself logs to the trace buffer, this flag should be set,
 *      otherwise it can be left unspecified.
 *
 * @NEEDS_REC: A flag that says whether or not this command needs
 *      access to the trace record in order to perform its function,
 *      regardless of whether or not it has a filter associated with
 *      it (filters make a trigger require access to the trace record
 *      but are not always present).
 */
enum event_command_flags {
        EVENT_CMD_FL_POST_TRIGGER       = 1,
        EVENT_CMD_FL_NEEDS_REC          = 2,
};

static inline bool event_command_post_trigger(struct event_command *cmd_ops)
{
        return cmd_ops->flags & EVENT_CMD_FL_POST_TRIGGER;
}

static inline bool event_command_needs_rec(struct event_command *cmd_ops)
{
        return cmd_ops->flags & EVENT_CMD_FL_NEEDS_REC;
}

extern int trace_event_enable_disable(struct trace_event_file *file,
                                      int enable, int soft_disable);
extern int tracing_alloc_snapshot(void);
extern void tracing_snapshot_cond(struct trace_array *tr, void *cond_data);
extern int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update);

extern int tracing_snapshot_cond_disable(struct trace_array *tr);
extern void *tracing_cond_snapshot_data(struct trace_array *tr);

extern const char *__start___trace_bprintk_fmt[];
extern const char *__stop___trace_bprintk_fmt[];

extern const char *__start___tracepoint_str[];
extern const char *__stop___tracepoint_str[];

void trace_printk_control(bool enabled);
void trace_printk_start_comm(void);
int trace_keep_overwrite(struct tracer *tracer, u32 mask, int set);
int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled);

/* Used from boot time tracer */
extern int trace_set_options(struct trace_array *tr, char *option);
extern int tracing_set_tracer(struct trace_array *tr, const char *buf);
extern ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
                                          unsigned long size, int cpu_id);
extern int tracing_set_cpumask(struct trace_array *tr,
                                cpumask_var_t tracing_cpumask_new);


#define MAX_EVENT_NAME_LEN      64

extern int trace_run_command(const char *buf, int (*createfn)(int, char**));
extern ssize_t trace_parse_run_command(struct file *file,
                const char __user *buffer, size_t count, loff_t *ppos,
                int (*createfn)(int, char**));

extern unsigned int err_pos(char *cmd, const char *str);
extern void tracing_log_err(struct trace_array *tr,
                            const char *loc, const char *cmd,
                            const char **errs, u8 type, u8 pos);

/*
 * Normal trace_printk() and friends allocates special buffers
 * to do the manipulation, as well as saves the print formats
 * into sections to display. But the trace infrastructure wants
 * to use these without the added overhead at the price of being
 * a bit slower (used mainly for warnings, where we don't care
 * about performance). The internal_trace_puts() is for such
 * a purpose.
 */
#define internal_trace_puts(str) __trace_puts(_THIS_IP_, str, strlen(str))

#undef FTRACE_ENTRY
#define FTRACE_ENTRY(call, struct_name, id, tstruct, print)     \
        extern struct trace_event_call                                  \
        __aligned(4) event_##call;
#undef FTRACE_ENTRY_DUP
#define FTRACE_ENTRY_DUP(call, struct_name, id, tstruct, print) \
        FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))
#undef FTRACE_ENTRY_PACKED
#define FTRACE_ENTRY_PACKED(call, struct_name, id, tstruct, print) \
        FTRACE_ENTRY(call, struct_name, id, PARAMS(tstruct), PARAMS(print))

#include "trace_entries.h"

#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_FUNCTION_TRACER)
int perf_ftrace_event_register(struct trace_event_call *call,
                               enum trace_reg type, void *data);
#else
#define perf_ftrace_event_register NULL
#endif

#ifdef CONFIG_FTRACE_SYSCALLS
void init_ftrace_syscalls(void);
const char *get_syscall_name(int syscall);
#else
static inline void init_ftrace_syscalls(void) { }
static inline const char *get_syscall_name(int syscall)
{
        return NULL;
}
#endif

#ifdef CONFIG_EVENT_TRACING
void trace_event_init(void);
void trace_event_eval_update(struct trace_eval_map **map, int len);
/* Used from boot time tracer */
extern int ftrace_set_clr_event(struct trace_array *tr, char *buf, int set);
extern int trigger_process_regex(struct trace_event_file *file, char *buff);
#else
static inline void __init trace_event_init(void) { }
static inline void trace_event_eval_update(struct trace_eval_map **map, int len) { }
#endif

#ifdef CONFIG_TRACER_SNAPSHOT
void tracing_snapshot_instance(struct trace_array *tr);
int tracing_alloc_snapshot_instance(struct trace_array *tr);
#else
static inline void tracing_snapshot_instance(struct trace_array *tr) { }
static inline int tracing_alloc_snapshot_instance(struct trace_array *tr)
{
        return 0;
}
#endif

#ifdef CONFIG_PREEMPT_TRACER
void tracer_preempt_on(unsigned long a0, unsigned long a1);
void tracer_preempt_off(unsigned long a0, unsigned long a1);
#else
static inline void tracer_preempt_on(unsigned long a0, unsigned long a1) { }
static inline void tracer_preempt_off(unsigned long a0, unsigned long a1) { }
#endif
#ifdef CONFIG_IRQSOFF_TRACER
void tracer_hardirqs_on(unsigned long a0, unsigned long a1);
void tracer_hardirqs_off(unsigned long a0, unsigned long a1);
#else
static inline void tracer_hardirqs_on(unsigned long a0, unsigned long a1) { }
static inline void tracer_hardirqs_off(unsigned long a0, unsigned long a1) { }
#endif

extern struct trace_iterator *tracepoint_print_iter;

/*
 * Reset the state of the trace_iterator so that it can read consumed data.
 * Normally, the trace_iterator is used for reading the data when it is not
 * consumed, and must retain state.
 */
static __always_inline void trace_iterator_reset(struct trace_iterator *iter)
{
        const size_t offset = offsetof(struct trace_iterator, seq);

        /*
         * Keep gcc from complaining about overwriting more than just one
         * member in the structure.
         */
        memset((char *)iter + offset, 0, sizeof(struct trace_iterator) - offset);

        iter->pos = -1;
}

#endif /* _LINUX_KERNEL_TRACE_H */