locking/rtmutex: Add mutex variant for RT
authorThomas Gleixner <tglx@linutronix.de>
Sun, 15 Aug 2021 21:29:01 +0000 (23:29 +0200)
committerIngo Molnar <mingo@kernel.org>
Tue, 17 Aug 2021 17:05:29 +0000 (19:05 +0200)
Add the necessary defines, helpers and API functions for replacing struct mutex on
a PREEMPT_RT enabled kernel with an rtmutex based variant.

No functional change when CONFIG_PREEMPT_RT=n

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.081517417@linutronix.de
include/linux/mutex.h
kernel/locking/mutex.c
kernel/locking/rtmutex_api.c
lib/Kconfig.debug

index 0bbc872..8f226d4 100644 (file)
 #include <linux/osq_lock.h>
 #include <linux/debug_locks.h>
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)                 \
+               , .dep_map = {                                  \
+                       .name = #lockname,                      \
+                       .wait_type_inner = LD_WAIT_SLEEP,       \
+               }
+#else
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
+#endif
+
+#ifndef CONFIG_PREEMPT_RT
+
 /*
  * Simple, straightforward mutexes with strict semantics:
  *
@@ -93,16 +105,6 @@ do {                                                                        \
        __mutex_init((mutex), #mutex, &__key);                          \
 } while (0)
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __DEP_MAP_MUTEX_INITIALIZER(lockname)                 \
-               , .dep_map = {                                  \
-                       .name = #lockname,                      \
-                       .wait_type_inner = LD_WAIT_SLEEP,       \
-               }
-#else
-# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
-#endif
-
 #define __MUTEX_INITIALIZER(lockname) \
                { .owner = ATOMIC_LONG_INIT(0) \
                , .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
@@ -124,6 +126,50 @@ extern void __mutex_init(struct mutex *lock, const char *name,
  */
 extern bool mutex_is_locked(struct mutex *lock);
 
+#else /* !CONFIG_PREEMPT_RT */
+/*
+ * Preempt-RT variant based on rtmutexes.
+ */
+#include <linux/rtmutex.h>
+
+struct mutex {
+       struct rt_mutex_base    rtmutex;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+       struct lockdep_map      dep_map;
+#endif
+};
+
+#define __MUTEX_INITIALIZER(mutexname)                                 \
+{                                                                      \
+       .rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex)       \
+       __DEP_MAP_MUTEX_INITIALIZER(mutexname)                          \
+}
+
+#define DEFINE_MUTEX(mutexname)                                                \
+       struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
+
+extern void __mutex_rt_init(struct mutex *lock, const char *name,
+                           struct lock_class_key *key);
+extern int mutex_trylock(struct mutex *lock);
+
+static inline void mutex_destroy(struct mutex *lock) { }
+
+#define mutex_is_locked(l)     rt_mutex_base_is_locked(&(l)->rtmutex)
+
+#define __mutex_init(mutex, name, key)                 \
+do {                                                   \
+       rt_mutex_base_init(&(mutex)->rtmutex);          \
+       __mutex_rt_init((mutex), name, key);            \
+} while (0)
+
+#define mutex_init(mutex)                              \
+do {                                                   \
+       static struct lock_class_key __key;             \
+                                                       \
+       __mutex_init((mutex), #mutex, &__key);          \
+} while (0)
+#endif /* CONFIG_PREEMPT_RT */
+
 /*
  * See kernel/locking/mutex.c for detailed documentation of these APIs.
  * Also see Documentation/locking/mutex-design.rst.
index 9906ca6..3a65bf4 100644 (file)
@@ -30,6 +30,7 @@
 #include <linux/debug_locks.h>
 #include <linux/osq_lock.h>
 
+#ifndef CONFIG_PREEMPT_RT
 #include "mutex.h"
 
 #ifdef CONFIG_DEBUG_MUTEXES
@@ -1066,7 +1067,8 @@ ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
 }
 EXPORT_SYMBOL(ww_mutex_lock_interruptible);
 
-#endif
+#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
+#endif /* !CONFIG_PREEMPT_RT */
 
 /**
  * atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
index 16126fc..92b7d28 100644 (file)
@@ -454,3 +454,125 @@ void rt_mutex_debug_task_free(struct task_struct *task)
        DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
 }
 #endif
+
+#ifdef CONFIG_PREEMPT_RT
+/* Mutexes */
+void __mutex_rt_init(struct mutex *mutex, const char *name,
+                    struct lock_class_key *key)
+{
+       debug_check_no_locks_freed((void *)mutex, sizeof(*mutex));
+       lockdep_init_map_wait(&mutex->dep_map, name, key, 0, LD_WAIT_SLEEP);
+}
+EXPORT_SYMBOL(__mutex_rt_init);
+
+static __always_inline int __mutex_lock_common(struct mutex *lock,
+                                              unsigned int state,
+                                              unsigned int subclass,
+                                              struct lockdep_map *nest_lock,
+                                              unsigned long ip)
+{
+       int ret;
+
+       might_sleep();
+       mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
+       ret = __rt_mutex_lock(&lock->rtmutex, state);
+       if (ret)
+               mutex_release(&lock->dep_map, ip);
+       else
+               lock_acquired(&lock->dep_map, ip);
+       return ret;
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+void __sched mutex_lock_nested(struct mutex *lock, unsigned int subclass)
+{
+       __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_nested);
+
+void __sched _mutex_lock_nest_lock(struct mutex *lock,
+                                  struct lockdep_map *nest_lock)
+{
+       __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest_lock, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
+
+int __sched mutex_lock_interruptible_nested(struct mutex *lock,
+                                           unsigned int subclass)
+{
+       return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, subclass, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
+
+int __sched mutex_lock_killable_nested(struct mutex *lock,
+                                           unsigned int subclass)
+{
+       return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
+
+void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
+{
+       int token;
+
+       might_sleep();
+
+       token = io_schedule_prepare();
+       __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
+       io_schedule_finish(token);
+}
+EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
+
+#else /* CONFIG_DEBUG_LOCK_ALLOC */
+
+void __sched mutex_lock(struct mutex *lock)
+{
+       __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL(mutex_lock);
+
+int __sched mutex_lock_interruptible(struct mutex *lock)
+{
+       return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL(mutex_lock_interruptible);
+
+int __sched mutex_lock_killable(struct mutex *lock)
+{
+       return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
+}
+EXPORT_SYMBOL(mutex_lock_killable);
+
+void __sched mutex_lock_io(struct mutex *lock)
+{
+       int token = io_schedule_prepare();
+
+       __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
+       io_schedule_finish(token);
+}
+EXPORT_SYMBOL(mutex_lock_io);
+#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
+
+int __sched mutex_trylock(struct mutex *lock)
+{
+       int ret;
+
+       if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
+               return 0;
+
+       ret = __rt_mutex_trylock(&lock->rtmutex);
+       if (ret)
+               mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+
+       return ret;
+}
+EXPORT_SYMBOL(mutex_trylock);
+
+void __sched mutex_unlock(struct mutex *lock)
+{
+       mutex_release(&lock->dep_map, _RET_IP_);
+       __rt_mutex_unlock(&lock->rtmutex);
+}
+EXPORT_SYMBOL(mutex_unlock);
+
+#endif /* CONFIG_PREEMPT_RT */
index 5ddd575..e5cdf98 100644 (file)
@@ -1235,7 +1235,7 @@ config PROVE_LOCKING
        depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
        select LOCKDEP
        select DEBUG_SPINLOCK
-       select DEBUG_MUTEXES
+       select DEBUG_MUTEXES if !PREEMPT_RT
        select DEBUG_RT_MUTEXES if RT_MUTEXES
        select DEBUG_RWSEMS
        select DEBUG_WW_MUTEX_SLOWPATH
@@ -1299,7 +1299,7 @@ config LOCK_STAT
        depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
        select LOCKDEP
        select DEBUG_SPINLOCK
-       select DEBUG_MUTEXES
+       select DEBUG_MUTEXES if !PREEMPT_RT
        select DEBUG_RT_MUTEXES if RT_MUTEXES
        select DEBUG_LOCK_ALLOC
        default n
@@ -1335,7 +1335,7 @@ config DEBUG_SPINLOCK
 
 config DEBUG_MUTEXES
        bool "Mutex debugging: basic checks"
-       depends on DEBUG_KERNEL
+       depends on DEBUG_KERNEL && !PREEMPT_RT
        help
         This feature allows mutex semantics violations to be detected and
         reported.
@@ -1345,7 +1345,8 @@ config DEBUG_WW_MUTEX_SLOWPATH
        depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
        select DEBUG_LOCK_ALLOC
        select DEBUG_SPINLOCK
-       select DEBUG_MUTEXES
+       select DEBUG_MUTEXES if !PREEMPT_RT
+       select DEBUG_RT_MUTEXES if PREEMPT_RT
        help
         This feature enables slowpath testing for w/w mutex users by
         injecting additional -EDEADLK wound/backoff cases. Together with
@@ -1368,7 +1369,7 @@ config DEBUG_LOCK_ALLOC
        bool "Lock debugging: detect incorrect freeing of live locks"
        depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT
        select DEBUG_SPINLOCK
-       select DEBUG_MUTEXES
+       select DEBUG_MUTEXES if !PREEMPT_RT
        select DEBUG_RT_MUTEXES if RT_MUTEXES
        select LOCKDEP
        help