mutex: Move ww_mutex definitions to ww_mutex.h
Move the definitions for wound/wait mutexes out to a separate header, ww_mutex.h. This reduces clutter in mutex.h, and increases readability. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Cc: Dave Airlie <airlied@gmail.com> Link: http://lkml.kernel.org/r/51D675DC.3000907@canonical.com [ Tidied up the code a bit. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Maarten Lankhorst
Ingo Molnar
parent
2e17c5a97e
commit
1b375dc307
5 changed files with 381 additions and 359 deletions
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@ -78,40 +78,6 @@ struct mutex_waiter {
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#endif
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};
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struct ww_class {
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atomic_long_t stamp;
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struct lock_class_key acquire_key;
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struct lock_class_key mutex_key;
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const char *acquire_name;
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const char *mutex_name;
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};
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struct ww_acquire_ctx {
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struct task_struct *task;
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unsigned long stamp;
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unsigned acquired;
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#ifdef CONFIG_DEBUG_MUTEXES
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unsigned done_acquire;
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struct ww_class *ww_class;
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struct ww_mutex *contending_lock;
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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struct lockdep_map dep_map;
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#endif
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#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
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unsigned deadlock_inject_interval;
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unsigned deadlock_inject_countdown;
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#endif
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};
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struct ww_mutex {
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struct mutex base;
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struct ww_acquire_ctx *ctx;
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#ifdef CONFIG_DEBUG_MUTEXES
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struct ww_class *ww_class;
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#endif
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};
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#ifdef CONFIG_DEBUG_MUTEXES
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# include <linux/mutex-debug.h>
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#else
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@ -136,11 +102,8 @@ static inline void mutex_destroy(struct mutex *lock) {}
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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# define __DEP_MAP_MUTEX_INITIALIZER(lockname) \
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, .dep_map = { .name = #lockname }
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# define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class) \
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, .ww_class = &ww_class
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#else
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# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
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# define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class)
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#endif
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#define __MUTEX_INITIALIZER(lockname) \
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@ -150,48 +113,12 @@ static inline void mutex_destroy(struct mutex *lock) {}
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__DEBUG_MUTEX_INITIALIZER(lockname) \
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__DEP_MAP_MUTEX_INITIALIZER(lockname) }
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#define __WW_CLASS_INITIALIZER(ww_class) \
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{ .stamp = ATOMIC_LONG_INIT(0) \
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, .acquire_name = #ww_class "_acquire" \
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, .mutex_name = #ww_class "_mutex" }
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#define __WW_MUTEX_INITIALIZER(lockname, class) \
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{ .base = { \__MUTEX_INITIALIZER(lockname) } \
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__WW_CLASS_MUTEX_INITIALIZER(lockname, class) }
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#define DEFINE_MUTEX(mutexname) \
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struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
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#define DEFINE_WW_CLASS(classname) \
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struct ww_class classname = __WW_CLASS_INITIALIZER(classname)
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#define DEFINE_WW_MUTEX(mutexname, ww_class) \
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struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class)
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extern void __mutex_init(struct mutex *lock, const char *name,
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struct lock_class_key *key);
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/**
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* ww_mutex_init - initialize the w/w mutex
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* @lock: the mutex to be initialized
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* @ww_class: the w/w class the mutex should belong to
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*
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* Initialize the w/w mutex to unlocked state and associate it with the given
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* class.
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*
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* It is not allowed to initialize an already locked mutex.
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*/
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static inline void ww_mutex_init(struct ww_mutex *lock,
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struct ww_class *ww_class)
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{
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__mutex_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
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lock->ctx = NULL;
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#ifdef CONFIG_DEBUG_MUTEXES
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lock->ww_class = ww_class;
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#endif
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}
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/**
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* mutex_is_locked - is the mutex locked
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* @lock: the mutex to be queried
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@ -246,291 +173,6 @@ extern int __must_check mutex_lock_killable(struct mutex *lock);
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extern int mutex_trylock(struct mutex *lock);
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extern void mutex_unlock(struct mutex *lock);
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/**
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* ww_acquire_init - initialize a w/w acquire context
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* @ctx: w/w acquire context to initialize
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* @ww_class: w/w class of the context
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*
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* Initializes an context to acquire multiple mutexes of the given w/w class.
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*
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* Context-based w/w mutex acquiring can be done in any order whatsoever within
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* a given lock class. Deadlocks will be detected and handled with the
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* wait/wound logic.
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*
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* Mixing of context-based w/w mutex acquiring and single w/w mutex locking can
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* result in undetected deadlocks and is so forbidden. Mixing different contexts
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* for the same w/w class when acquiring mutexes can also result in undetected
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* deadlocks, and is hence also forbidden. Both types of abuse will be caught by
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* enabling CONFIG_PROVE_LOCKING.
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*
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* Nesting of acquire contexts for _different_ w/w classes is possible, subject
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* to the usual locking rules between different lock classes.
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*
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* An acquire context must be released with ww_acquire_fini by the same task
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* before the memory is freed. It is recommended to allocate the context itself
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* on the stack.
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*/
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static inline void ww_acquire_init(struct ww_acquire_ctx *ctx,
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struct ww_class *ww_class)
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{
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ctx->task = current;
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ctx->stamp = atomic_long_inc_return(&ww_class->stamp);
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ctx->acquired = 0;
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#ifdef CONFIG_DEBUG_MUTEXES
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ctx->ww_class = ww_class;
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ctx->done_acquire = 0;
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ctx->contending_lock = NULL;
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#endif
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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debug_check_no_locks_freed((void *)ctx, sizeof(*ctx));
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lockdep_init_map(&ctx->dep_map, ww_class->acquire_name,
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&ww_class->acquire_key, 0);
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mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_);
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#endif
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#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
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ctx->deadlock_inject_interval = 1;
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ctx->deadlock_inject_countdown = ctx->stamp & 0xf;
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#endif
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}
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/**
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* ww_acquire_done - marks the end of the acquire phase
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* @ctx: the acquire context
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*
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* Marks the end of the acquire phase, any further w/w mutex lock calls using
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* this context are forbidden.
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*
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* Calling this function is optional, it is just useful to document w/w mutex
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* code and clearly designated the acquire phase from actually using the locked
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* data structures.
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*/
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static inline void ww_acquire_done(struct ww_acquire_ctx *ctx)
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{
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#ifdef CONFIG_DEBUG_MUTEXES
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lockdep_assert_held(ctx);
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DEBUG_LOCKS_WARN_ON(ctx->done_acquire);
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ctx->done_acquire = 1;
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#endif
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}
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/**
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* ww_acquire_fini - releases a w/w acquire context
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* @ctx: the acquire context to free
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*
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* Releases a w/w acquire context. This must be called _after_ all acquired w/w
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* mutexes have been released with ww_mutex_unlock.
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*/
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static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
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{
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#ifdef CONFIG_DEBUG_MUTEXES
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mutex_release(&ctx->dep_map, 0, _THIS_IP_);
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DEBUG_LOCKS_WARN_ON(ctx->acquired);
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if (!config_enabled(CONFIG_PROVE_LOCKING))
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/*
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* lockdep will normally handle this,
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* but fail without anyway
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*/
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ctx->done_acquire = 1;
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if (!config_enabled(CONFIG_DEBUG_LOCK_ALLOC))
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/* ensure ww_acquire_fini will still fail if called twice */
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ctx->acquired = ~0U;
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#endif
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}
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extern int __must_check __ww_mutex_lock(struct ww_mutex *lock,
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struct ww_acquire_ctx *ctx);
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extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock,
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struct ww_acquire_ctx *ctx);
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/**
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* ww_mutex_lock - acquire the w/w mutex
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* @lock: the mutex to be acquired
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* @ctx: w/w acquire context, or NULL to acquire only a single lock.
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*
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* Lock the w/w mutex exclusively for this task.
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*
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* Deadlocks within a given w/w class of locks are detected and handled with the
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* wait/wound algorithm. If the lock isn't immediately avaiable this function
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* will either sleep until it is (wait case). Or it selects the current context
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* for backing off by returning -EDEADLK (wound case). Trying to acquire the
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* same lock with the same context twice is also detected and signalled by
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* returning -EALREADY. Returns 0 if the mutex was successfully acquired.
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*
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* In the wound case the caller must release all currently held w/w mutexes for
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* the given context and then wait for this contending lock to be available by
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* calling ww_mutex_lock_slow. Alternatively callers can opt to not acquire this
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* lock and proceed with trying to acquire further w/w mutexes (e.g. when
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* scanning through lru lists trying to free resources).
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*
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* The mutex must later on be released by the same task that
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* acquired it. The task may not exit without first unlocking the mutex. Also,
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* kernel memory where the mutex resides must not be freed with the mutex still
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* locked. The mutex must first be initialized (or statically defined) before it
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* can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
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* of the same w/w lock class as was used to initialize the acquire context.
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*
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* A mutex acquired with this function must be released with ww_mutex_unlock.
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*/
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static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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if (ctx)
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return __ww_mutex_lock(lock, ctx);
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else {
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mutex_lock(&lock->base);
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return 0;
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}
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}
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/**
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* ww_mutex_lock_interruptible - acquire the w/w mutex, interruptible
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* @lock: the mutex to be acquired
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* @ctx: w/w acquire context
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*
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* Lock the w/w mutex exclusively for this task.
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*
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* Deadlocks within a given w/w class of locks are detected and handled with the
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* wait/wound algorithm. If the lock isn't immediately avaiable this function
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* will either sleep until it is (wait case). Or it selects the current context
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* for backing off by returning -EDEADLK (wound case). Trying to acquire the
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* same lock with the same context twice is also detected and signalled by
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* returning -EALREADY. Returns 0 if the mutex was successfully acquired. If a
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* signal arrives while waiting for the lock then this function returns -EINTR.
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*
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* In the wound case the caller must release all currently held w/w mutexes for
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* the given context and then wait for this contending lock to be available by
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* calling ww_mutex_lock_slow_interruptible. Alternatively callers can opt to
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* not acquire this lock and proceed with trying to acquire further w/w mutexes
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* (e.g. when scanning through lru lists trying to free resources).
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*
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* The mutex must later on be released by the same task that
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* acquired it. The task may not exit without first unlocking the mutex. Also,
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* kernel memory where the mutex resides must not be freed with the mutex still
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* locked. The mutex must first be initialized (or statically defined) before it
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* can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
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* of the same w/w lock class as was used to initialize the acquire context.
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*
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* A mutex acquired with this function must be released with ww_mutex_unlock.
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*/
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static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock,
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struct ww_acquire_ctx *ctx)
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{
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if (ctx)
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return __ww_mutex_lock_interruptible(lock, ctx);
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else
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return mutex_lock_interruptible(&lock->base);
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}
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/**
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* ww_mutex_lock_slow - slowpath acquiring of the w/w mutex
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* @lock: the mutex to be acquired
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* @ctx: w/w acquire context
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*
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* Acquires a w/w mutex with the given context after a wound case. This function
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* will sleep until the lock becomes available.
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*
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* The caller must have released all w/w mutexes already acquired with the
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* context and then call this function on the contended lock.
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*
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* Afterwards the caller may continue to (re)acquire the other w/w mutexes it
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* needs with ww_mutex_lock. Note that the -EALREADY return code from
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* ww_mutex_lock can be used to avoid locking this contended mutex twice.
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*
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* It is forbidden to call this function with any other w/w mutexes associated
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* with the context held. It is forbidden to call this on anything else than the
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* contending mutex.
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*
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* Note that the slowpath lock acquiring can also be done by calling
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* ww_mutex_lock directly. This function here is simply to help w/w mutex
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* locking code readability by clearly denoting the slowpath.
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*/
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static inline void
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ww_mutex_lock_slow(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
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{
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int ret;
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#ifdef CONFIG_DEBUG_MUTEXES
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DEBUG_LOCKS_WARN_ON(!ctx->contending_lock);
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#endif
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ret = ww_mutex_lock(lock, ctx);
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(void)ret;
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}
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/**
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* ww_mutex_lock_slow_interruptible - slowpath acquiring of the w/w mutex,
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* interruptible
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* @lock: the mutex to be acquired
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* @ctx: w/w acquire context
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*
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* Acquires a w/w mutex with the given context after a wound case. This function
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* will sleep until the lock becomes available and returns 0 when the lock has
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* been acquired. If a signal arrives while waiting for the lock then this
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* function returns -EINTR.
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*
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* The caller must have released all w/w mutexes already acquired with the
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* context and then call this function on the contended lock.
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*
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* Afterwards the caller may continue to (re)acquire the other w/w mutexes it
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* needs with ww_mutex_lock. Note that the -EALREADY return code from
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* ww_mutex_lock can be used to avoid locking this contended mutex twice.
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*
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* It is forbidden to call this function with any other w/w mutexes associated
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* with the given context held. It is forbidden to call this on anything else
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* than the contending mutex.
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*
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* Note that the slowpath lock acquiring can also be done by calling
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* ww_mutex_lock_interruptible directly. This function here is simply to help
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* w/w mutex locking code readability by clearly denoting the slowpath.
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*/
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static inline int __must_check
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ww_mutex_lock_slow_interruptible(struct ww_mutex *lock,
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struct ww_acquire_ctx *ctx)
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{
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#ifdef CONFIG_DEBUG_MUTEXES
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DEBUG_LOCKS_WARN_ON(!ctx->contending_lock);
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#endif
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return ww_mutex_lock_interruptible(lock, ctx);
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}
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extern void ww_mutex_unlock(struct ww_mutex *lock);
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/**
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* ww_mutex_trylock - tries to acquire the w/w mutex without acquire context
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* @lock: mutex to lock
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*
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* Trylocks a mutex without acquire context, so no deadlock detection is
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* possible. Returns 1 if the mutex has been acquired successfully, 0 otherwise.
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*/
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static inline int __must_check ww_mutex_trylock(struct ww_mutex *lock)
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{
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return mutex_trylock(&lock->base);
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}
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/***
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* ww_mutex_destroy - mark a w/w mutex unusable
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* @lock: the mutex to be destroyed
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*
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* This function marks the mutex uninitialized, and any subsequent
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* use of the mutex is forbidden. The mutex must not be locked when
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* this function is called.
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*/
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static inline void ww_mutex_destroy(struct ww_mutex *lock)
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{
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mutex_destroy(&lock->base);
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}
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/**
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* ww_mutex_is_locked - is the w/w mutex locked
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* @lock: the mutex to be queried
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*
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* Returns 1 if the mutex is locked, 0 if unlocked.
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*/
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static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
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{
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return mutex_is_locked(&lock->base);
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}
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extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
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#ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX
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@ -39,7 +39,7 @@
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#ifndef _LINUX_RESERVATION_H
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#define _LINUX_RESERVATION_H
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#include <linux/mutex.h>
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#include <linux/ww_mutex.h>
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extern struct ww_class reservation_ww_class;
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378
include/linux/ww_mutex.h
Normal file
378
include/linux/ww_mutex.h
Normal file
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@ -0,0 +1,378 @@
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/*
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* Wound/Wait Mutexes: blocking mutual exclusion locks with deadlock avoidance
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*
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* Original mutex implementation started by Ingo Molnar:
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*
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* Copyright (C) 2004, 2005, 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* Wound/wait implementation:
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* Copyright (C) 2013 Canonical Ltd.
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*
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* This file contains the main data structure and API definitions.
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*/
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#ifndef __LINUX_WW_MUTEX_H
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#define __LINUX_WW_MUTEX_H
|
||||
|
||||
#include <linux/mutex.h>
|
||||
|
||||
struct ww_class {
|
||||
atomic_long_t stamp;
|
||||
struct lock_class_key acquire_key;
|
||||
struct lock_class_key mutex_key;
|
||||
const char *acquire_name;
|
||||
const char *mutex_name;
|
||||
};
|
||||
|
||||
struct ww_acquire_ctx {
|
||||
struct task_struct *task;
|
||||
unsigned long stamp;
|
||||
unsigned acquired;
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
unsigned done_acquire;
|
||||
struct ww_class *ww_class;
|
||||
struct ww_mutex *contending_lock;
|
||||
#endif
|
||||
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
||||
struct lockdep_map dep_map;
|
||||
#endif
|
||||
#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
|
||||
unsigned deadlock_inject_interval;
|
||||
unsigned deadlock_inject_countdown;
|
||||
#endif
|
||||
};
|
||||
|
||||
struct ww_mutex {
|
||||
struct mutex base;
|
||||
struct ww_acquire_ctx *ctx;
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
struct ww_class *ww_class;
|
||||
#endif
|
||||
};
|
||||
|
||||
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
||||
# define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class) \
|
||||
, .ww_class = &ww_class
|
||||
#else
|
||||
# define __WW_CLASS_MUTEX_INITIALIZER(lockname, ww_class)
|
||||
#endif
|
||||
|
||||
#define __WW_CLASS_INITIALIZER(ww_class) \
|
||||
{ .stamp = ATOMIC_LONG_INIT(0) \
|
||||
, .acquire_name = #ww_class "_acquire" \
|
||||
, .mutex_name = #ww_class "_mutex" }
|
||||
|
||||
#define __WW_MUTEX_INITIALIZER(lockname, class) \
|
||||
{ .base = { \__MUTEX_INITIALIZER(lockname) } \
|
||||
__WW_CLASS_MUTEX_INITIALIZER(lockname, class) }
|
||||
|
||||
#define DEFINE_WW_CLASS(classname) \
|
||||
struct ww_class classname = __WW_CLASS_INITIALIZER(classname)
|
||||
|
||||
#define DEFINE_WW_MUTEX(mutexname, ww_class) \
|
||||
struct ww_mutex mutexname = __WW_MUTEX_INITIALIZER(mutexname, ww_class)
|
||||
|
||||
/**
|
||||
* ww_mutex_init - initialize the w/w mutex
|
||||
* @lock: the mutex to be initialized
|
||||
* @ww_class: the w/w class the mutex should belong to
|
||||
*
|
||||
* Initialize the w/w mutex to unlocked state and associate it with the given
|
||||
* class.
|
||||
*
|
||||
* It is not allowed to initialize an already locked mutex.
|
||||
*/
|
||||
static inline void ww_mutex_init(struct ww_mutex *lock,
|
||||
struct ww_class *ww_class)
|
||||
{
|
||||
__mutex_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
|
||||
lock->ctx = NULL;
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
lock->ww_class = ww_class;
|
||||
#endif
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_acquire_init - initialize a w/w acquire context
|
||||
* @ctx: w/w acquire context to initialize
|
||||
* @ww_class: w/w class of the context
|
||||
*
|
||||
* Initializes an context to acquire multiple mutexes of the given w/w class.
|
||||
*
|
||||
* Context-based w/w mutex acquiring can be done in any order whatsoever within
|
||||
* a given lock class. Deadlocks will be detected and handled with the
|
||||
* wait/wound logic.
|
||||
*
|
||||
* Mixing of context-based w/w mutex acquiring and single w/w mutex locking can
|
||||
* result in undetected deadlocks and is so forbidden. Mixing different contexts
|
||||
* for the same w/w class when acquiring mutexes can also result in undetected
|
||||
* deadlocks, and is hence also forbidden. Both types of abuse will be caught by
|
||||
* enabling CONFIG_PROVE_LOCKING.
|
||||
*
|
||||
* Nesting of acquire contexts for _different_ w/w classes is possible, subject
|
||||
* to the usual locking rules between different lock classes.
|
||||
*
|
||||
* An acquire context must be released with ww_acquire_fini by the same task
|
||||
* before the memory is freed. It is recommended to allocate the context itself
|
||||
* on the stack.
|
||||
*/
|
||||
static inline void ww_acquire_init(struct ww_acquire_ctx *ctx,
|
||||
struct ww_class *ww_class)
|
||||
{
|
||||
ctx->task = current;
|
||||
ctx->stamp = atomic_long_inc_return(&ww_class->stamp);
|
||||
ctx->acquired = 0;
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
ctx->ww_class = ww_class;
|
||||
ctx->done_acquire = 0;
|
||||
ctx->contending_lock = NULL;
|
||||
#endif
|
||||
#ifdef CONFIG_DEBUG_LOCK_ALLOC
|
||||
debug_check_no_locks_freed((void *)ctx, sizeof(*ctx));
|
||||
lockdep_init_map(&ctx->dep_map, ww_class->acquire_name,
|
||||
&ww_class->acquire_key, 0);
|
||||
mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_);
|
||||
#endif
|
||||
#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH
|
||||
ctx->deadlock_inject_interval = 1;
|
||||
ctx->deadlock_inject_countdown = ctx->stamp & 0xf;
|
||||
#endif
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_acquire_done - marks the end of the acquire phase
|
||||
* @ctx: the acquire context
|
||||
*
|
||||
* Marks the end of the acquire phase, any further w/w mutex lock calls using
|
||||
* this context are forbidden.
|
||||
*
|
||||
* Calling this function is optional, it is just useful to document w/w mutex
|
||||
* code and clearly designated the acquire phase from actually using the locked
|
||||
* data structures.
|
||||
*/
|
||||
static inline void ww_acquire_done(struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
lockdep_assert_held(ctx);
|
||||
|
||||
DEBUG_LOCKS_WARN_ON(ctx->done_acquire);
|
||||
ctx->done_acquire = 1;
|
||||
#endif
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_acquire_fini - releases a w/w acquire context
|
||||
* @ctx: the acquire context to free
|
||||
*
|
||||
* Releases a w/w acquire context. This must be called _after_ all acquired w/w
|
||||
* mutexes have been released with ww_mutex_unlock.
|
||||
*/
|
||||
static inline void ww_acquire_fini(struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
mutex_release(&ctx->dep_map, 0, _THIS_IP_);
|
||||
|
||||
DEBUG_LOCKS_WARN_ON(ctx->acquired);
|
||||
if (!config_enabled(CONFIG_PROVE_LOCKING))
|
||||
/*
|
||||
* lockdep will normally handle this,
|
||||
* but fail without anyway
|
||||
*/
|
||||
ctx->done_acquire = 1;
|
||||
|
||||
if (!config_enabled(CONFIG_DEBUG_LOCK_ALLOC))
|
||||
/* ensure ww_acquire_fini will still fail if called twice */
|
||||
ctx->acquired = ~0U;
|
||||
#endif
|
||||
}
|
||||
|
||||
extern int __must_check __ww_mutex_lock(struct ww_mutex *lock,
|
||||
struct ww_acquire_ctx *ctx);
|
||||
extern int __must_check __ww_mutex_lock_interruptible(struct ww_mutex *lock,
|
||||
struct ww_acquire_ctx *ctx);
|
||||
|
||||
/**
|
||||
* ww_mutex_lock - acquire the w/w mutex
|
||||
* @lock: the mutex to be acquired
|
||||
* @ctx: w/w acquire context, or NULL to acquire only a single lock.
|
||||
*
|
||||
* Lock the w/w mutex exclusively for this task.
|
||||
*
|
||||
* Deadlocks within a given w/w class of locks are detected and handled with the
|
||||
* wait/wound algorithm. If the lock isn't immediately avaiable this function
|
||||
* will either sleep until it is (wait case). Or it selects the current context
|
||||
* for backing off by returning -EDEADLK (wound case). Trying to acquire the
|
||||
* same lock with the same context twice is also detected and signalled by
|
||||
* returning -EALREADY. Returns 0 if the mutex was successfully acquired.
|
||||
*
|
||||
* In the wound case the caller must release all currently held w/w mutexes for
|
||||
* the given context and then wait for this contending lock to be available by
|
||||
* calling ww_mutex_lock_slow. Alternatively callers can opt to not acquire this
|
||||
* lock and proceed with trying to acquire further w/w mutexes (e.g. when
|
||||
* scanning through lru lists trying to free resources).
|
||||
*
|
||||
* The mutex must later on be released by the same task that
|
||||
* acquired it. The task may not exit without first unlocking the mutex. Also,
|
||||
* kernel memory where the mutex resides must not be freed with the mutex still
|
||||
* locked. The mutex must first be initialized (or statically defined) before it
|
||||
* can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
|
||||
* of the same w/w lock class as was used to initialize the acquire context.
|
||||
*
|
||||
* A mutex acquired with this function must be released with ww_mutex_unlock.
|
||||
*/
|
||||
static inline int ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
if (ctx)
|
||||
return __ww_mutex_lock(lock, ctx);
|
||||
|
||||
mutex_lock(&lock->base);
|
||||
return 0;
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_mutex_lock_interruptible - acquire the w/w mutex, interruptible
|
||||
* @lock: the mutex to be acquired
|
||||
* @ctx: w/w acquire context
|
||||
*
|
||||
* Lock the w/w mutex exclusively for this task.
|
||||
*
|
||||
* Deadlocks within a given w/w class of locks are detected and handled with the
|
||||
* wait/wound algorithm. If the lock isn't immediately avaiable this function
|
||||
* will either sleep until it is (wait case). Or it selects the current context
|
||||
* for backing off by returning -EDEADLK (wound case). Trying to acquire the
|
||||
* same lock with the same context twice is also detected and signalled by
|
||||
* returning -EALREADY. Returns 0 if the mutex was successfully acquired. If a
|
||||
* signal arrives while waiting for the lock then this function returns -EINTR.
|
||||
*
|
||||
* In the wound case the caller must release all currently held w/w mutexes for
|
||||
* the given context and then wait for this contending lock to be available by
|
||||
* calling ww_mutex_lock_slow_interruptible. Alternatively callers can opt to
|
||||
* not acquire this lock and proceed with trying to acquire further w/w mutexes
|
||||
* (e.g. when scanning through lru lists trying to free resources).
|
||||
*
|
||||
* The mutex must later on be released by the same task that
|
||||
* acquired it. The task may not exit without first unlocking the mutex. Also,
|
||||
* kernel memory where the mutex resides must not be freed with the mutex still
|
||||
* locked. The mutex must first be initialized (or statically defined) before it
|
||||
* can be locked. memset()-ing the mutex to 0 is not allowed. The mutex must be
|
||||
* of the same w/w lock class as was used to initialize the acquire context.
|
||||
*
|
||||
* A mutex acquired with this function must be released with ww_mutex_unlock.
|
||||
*/
|
||||
static inline int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock,
|
||||
struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
if (ctx)
|
||||
return __ww_mutex_lock_interruptible(lock, ctx);
|
||||
else
|
||||
return mutex_lock_interruptible(&lock->base);
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_mutex_lock_slow - slowpath acquiring of the w/w mutex
|
||||
* @lock: the mutex to be acquired
|
||||
* @ctx: w/w acquire context
|
||||
*
|
||||
* Acquires a w/w mutex with the given context after a wound case. This function
|
||||
* will sleep until the lock becomes available.
|
||||
*
|
||||
* The caller must have released all w/w mutexes already acquired with the
|
||||
* context and then call this function on the contended lock.
|
||||
*
|
||||
* Afterwards the caller may continue to (re)acquire the other w/w mutexes it
|
||||
* needs with ww_mutex_lock. Note that the -EALREADY return code from
|
||||
* ww_mutex_lock can be used to avoid locking this contended mutex twice.
|
||||
*
|
||||
* It is forbidden to call this function with any other w/w mutexes associated
|
||||
* with the context held. It is forbidden to call this on anything else than the
|
||||
* contending mutex.
|
||||
*
|
||||
* Note that the slowpath lock acquiring can also be done by calling
|
||||
* ww_mutex_lock directly. This function here is simply to help w/w mutex
|
||||
* locking code readability by clearly denoting the slowpath.
|
||||
*/
|
||||
static inline void
|
||||
ww_mutex_lock_slow(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
int ret;
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
DEBUG_LOCKS_WARN_ON(!ctx->contending_lock);
|
||||
#endif
|
||||
ret = ww_mutex_lock(lock, ctx);
|
||||
(void)ret;
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_mutex_lock_slow_interruptible - slowpath acquiring of the w/w mutex, interruptible
|
||||
* @lock: the mutex to be acquired
|
||||
* @ctx: w/w acquire context
|
||||
*
|
||||
* Acquires a w/w mutex with the given context after a wound case. This function
|
||||
* will sleep until the lock becomes available and returns 0 when the lock has
|
||||
* been acquired. If a signal arrives while waiting for the lock then this
|
||||
* function returns -EINTR.
|
||||
*
|
||||
* The caller must have released all w/w mutexes already acquired with the
|
||||
* context and then call this function on the contended lock.
|
||||
*
|
||||
* Afterwards the caller may continue to (re)acquire the other w/w mutexes it
|
||||
* needs with ww_mutex_lock. Note that the -EALREADY return code from
|
||||
* ww_mutex_lock can be used to avoid locking this contended mutex twice.
|
||||
*
|
||||
* It is forbidden to call this function with any other w/w mutexes associated
|
||||
* with the given context held. It is forbidden to call this on anything else
|
||||
* than the contending mutex.
|
||||
*
|
||||
* Note that the slowpath lock acquiring can also be done by calling
|
||||
* ww_mutex_lock_interruptible directly. This function here is simply to help
|
||||
* w/w mutex locking code readability by clearly denoting the slowpath.
|
||||
*/
|
||||
static inline int __must_check
|
||||
ww_mutex_lock_slow_interruptible(struct ww_mutex *lock,
|
||||
struct ww_acquire_ctx *ctx)
|
||||
{
|
||||
#ifdef CONFIG_DEBUG_MUTEXES
|
||||
DEBUG_LOCKS_WARN_ON(!ctx->contending_lock);
|
||||
#endif
|
||||
return ww_mutex_lock_interruptible(lock, ctx);
|
||||
}
|
||||
|
||||
extern void ww_mutex_unlock(struct ww_mutex *lock);
|
||||
|
||||
/**
|
||||
* ww_mutex_trylock - tries to acquire the w/w mutex without acquire context
|
||||
* @lock: mutex to lock
|
||||
*
|
||||
* Trylocks a mutex without acquire context, so no deadlock detection is
|
||||
* possible. Returns 1 if the mutex has been acquired successfully, 0 otherwise.
|
||||
*/
|
||||
static inline int __must_check ww_mutex_trylock(struct ww_mutex *lock)
|
||||
{
|
||||
return mutex_trylock(&lock->base);
|
||||
}
|
||||
|
||||
/***
|
||||
* ww_mutex_destroy - mark a w/w mutex unusable
|
||||
* @lock: the mutex to be destroyed
|
||||
*
|
||||
* This function marks the mutex uninitialized, and any subsequent
|
||||
* use of the mutex is forbidden. The mutex must not be locked when
|
||||
* this function is called.
|
||||
*/
|
||||
static inline void ww_mutex_destroy(struct ww_mutex *lock)
|
||||
{
|
||||
mutex_destroy(&lock->base);
|
||||
}
|
||||
|
||||
/**
|
||||
* ww_mutex_is_locked - is the w/w mutex locked
|
||||
* @lock: the mutex to be queried
|
||||
*
|
||||
* Returns 1 if the mutex is locked, 0 if unlocked.
|
||||
*/
|
||||
static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
|
||||
{
|
||||
return mutex_is_locked(&lock->base);
|
||||
}
|
||||
|
||||
#endif
|
||||
|
|
@ -18,6 +18,7 @@
|
|||
* Also see Documentation/mutex-design.txt.
|
||||
*/
|
||||
#include <linux/mutex.h>
|
||||
#include <linux/ww_mutex.h>
|
||||
#include <linux/sched.h>
|
||||
#include <linux/sched/rt.h>
|
||||
#include <linux/export.h>
|
||||
|
|
|
|||
|
|
@ -12,6 +12,7 @@
|
|||
*/
|
||||
#include <linux/rwsem.h>
|
||||
#include <linux/mutex.h>
|
||||
#include <linux/ww_mutex.h>
|
||||
#include <linux/sched.h>
|
||||
#include <linux/delay.h>
|
||||
#include <linux/lockdep.h>
|
||||
|
|
|
|||
Loading…
Reference in a new issue