kernel/locking/rtmutex-debug.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * RT-Mutexes: blocking mutual exclusion locks with PI support
   4  *
   5  * started by Ingo Molnar and Thomas Gleixner:
   6  *
   7  *  Copyright (C) 2004-2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   8  *  Copyright (C) 2006 Timesys Corp., Thomas Gleixner <tglx@timesys.com>
   9  *
  10  * This code is based on the rt.c implementation in the preempt-rt tree.
  11  * Portions of said code are
  12  *
  13  *  Copyright (C) 2004  LynuxWorks, Inc., Igor Manyilov, Bill Huey
  14  *  Copyright (C) 2006  Esben Nielsen
  15  *  Copyright (C) 2006  Kihon Technologies Inc.,
  16  *                      Steven Rostedt <rostedt@goodmis.org>
  17  *
  18  * See rt.c in preempt-rt for proper credits and further information
  19  */
  20 #include <linux/sched.h>
  21 #include <linux/sched/rt.h>
  22 #include <linux/sched/debug.h>
  23 #include <linux/delay.h>
  24 #include <linux/export.h>
  25 #include <linux/spinlock.h>
  26 #include <linux/kallsyms.h>
  27 #include <linux/syscalls.h>
  28 #include <linux/interrupt.h>
  29 #include <linux/rbtree.h>
  30 #include <linux/fs.h>
  31 #include <linux/debug_locks.h>
  32
  33 #include "rtmutex_common.h"
  34
  35 static void printk_task(struct task_struct *p)
  36 {
  37         if (p)
  38                 printk("%16s:%5d [%p, %3d]", p->comm, task_pid_nr(p), p, p->prio);
  39         else
  40                 printk("<none>");
  41 }
  42
  43 static void printk_lock(struct rt_mutex *lock, int print_owner)
  44 {
  45         if (lock->name)
  46                 printk(" [%p] {%s}\n",
  47                         lock, lock->name);
  48         else
  49                 printk(" [%p] {%s:%d}\n",
  50                         lock, lock->file, lock->line);
  51
  52         if (print_owner && rt_mutex_owner(lock)) {
  53                 printk(".. ->owner: %p\n", lock->owner);
  54                 printk(".. held by:  ");
  55                 printk_task(rt_mutex_owner(lock));
  56                 printk("\n");
  57         }
  58 }
  59
  60 void rt_mutex_debug_task_free(struct task_struct *task)
  61 {
  62         DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
  63         DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
  64 }
  65
  66 /*
  67  * We fill out the fields in the waiter to store the information about
  68  * the deadlock. We print when we return. act_waiter can be NULL in
  69  * case of a remove waiter operation.
  70  */
  71 void debug_rt_mutex_deadlock(enum rtmutex_chainwalk chwalk,
  72                              struct rt_mutex_waiter *act_waiter,
  73                              struct rt_mutex *lock)
  74 {
  75         struct task_struct *task;
  76
  77         if (!debug_locks || chwalk == RT_MUTEX_FULL_CHAINWALK || !act_waiter)
  78                 return;
  79
  80         task = rt_mutex_owner(act_waiter->lock);
  81         if (task && task != current) {
  82                 act_waiter->deadlock_task_pid = get_pid(task_pid(task));
  83                 act_waiter->deadlock_lock = lock;
  84         }
  85 }
  86
  87 void debug_rt_mutex_print_deadlock(struct rt_mutex_waiter *waiter)
  88 {
  89         struct task_struct *task;
  90
  91         if (!waiter->deadlock_lock || !debug_locks)
  92                 return;
  93
  94         rcu_read_lock();
  95         task = pid_task(waiter->deadlock_task_pid, PIDTYPE_PID);
  96         if (!task) {
  97                 rcu_read_unlock();
  98                 return;
  99         }
 100
 101         if (!debug_locks_off()) {
 102                 rcu_read_unlock();
 103                 return;
 104         }
 105
 106         pr_warn("\n");
 107         pr_warn("============================================\n");
 108         pr_warn("WARNING: circular locking deadlock detected!\n");
 109         pr_warn("%s\n", print_tainted());
 110         pr_warn("--------------------------------------------\n");
 111         printk("%s/%d is deadlocking current task %s/%d\n\n",
 112                task->comm, task_pid_nr(task),
 113                current->comm, task_pid_nr(current));
 114
 115         printk("\n1) %s/%d is trying to acquire this lock:\n",
 116                current->comm, task_pid_nr(current));
 117         printk_lock(waiter->lock, 1);
 118
 119         printk("\n2) %s/%d is blocked on this lock:\n",
 120                 task->comm, task_pid_nr(task));
 121         printk_lock(waiter->deadlock_lock, 1);
 122
 123         debug_show_held_locks(current);
 124         debug_show_held_locks(task);
 125
 126         printk("\n%s/%d's [blocked] stackdump:\n\n",
 127                 task->comm, task_pid_nr(task));
 128         show_stack(task, NULL);
 129         printk("\n%s/%d's [current] stackdump:\n\n",
 130                 current->comm, task_pid_nr(current));
 131         dump_stack();
 132         debug_show_all_locks();
 133         rcu_read_unlock();
 134
 135         printk("[ turning off deadlock detection."
 136                "Please report this trace. ]\n\n");
 137 }
 138
 139 void debug_rt_mutex_lock(struct rt_mutex *lock)
 140 {
 141 }
 142
 143 void debug_rt_mutex_unlock(struct rt_mutex *lock)
 144 {
 145         DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current);
 146 }
 147
 148 void
 149 debug_rt_mutex_proxy_lock(struct rt_mutex *lock, struct task_struct *powner)
 150 {
 151 }
 152
 153 void debug_rt_mutex_proxy_unlock(struct rt_mutex *lock)
 154 {
 155         DEBUG_LOCKS_WARN_ON(!rt_mutex_owner(lock));
 156 }
 157
 158 void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
 159 {
 160         memset(waiter, 0x11, sizeof(*waiter));
 161         waiter->deadlock_task_pid = NULL;
 162 }
 163
 164 void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
 165 {
 166         put_pid(waiter->deadlock_task_pid);
 167         memset(waiter, 0x22, sizeof(*waiter));
 168 }
 169
 170 void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key)
 171 {
 172         /*
 173          * Make sure we are not reinitializing a held lock:
 174          */
 175         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
 176         lock->name = name;
 177
 178 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 179         lockdep_init_map(&lock->dep_map, name, key, 0);
 180 #endif
 181 }
 182