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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#ifndef __LINUX_WW_MUTEX_H#define __LINUX_WW_MUTEX_H
#include <linux/instruction_pointer.h>#include <linux/mutex.h>#include <linux/rtmutex.h>
#if defined(CONFIG_DEBUG_MUTEXES) || \ (defined(CONFIG_PREEMPT_RT) && defined(CONFIG_DEBUG_RT_MUTEXES))#define DEBUG_WW_MUTEXES#endif
#ifndef CONFIG_PREEMPT_RT#define WW_MUTEX_BASE mutex#define ww_mutex_base_init(l,n,k) __mutex_init(l,n,k)#define ww_mutex_base_is_locked(b) mutex_is_locked((b))#else#define WW_MUTEX_BASE rt_mutex#define ww_mutex_base_init(l,n,k) __rt_mutex_init(l,n,k)#define ww_mutex_base_is_locked(b) rt_mutex_base_is_locked(&(b)->rtmutex)#endif
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; unsigned int is_wait_die;};
context_lock_struct(ww_mutex) { struct WW_MUTEX_BASE base; struct ww_acquire_ctx *ctx;#ifdef DEBUG_WW_MUTEXES struct ww_class *ww_class;#endif};
context_lock_struct(ww_acquire_ctx) { struct task_struct *task; unsigned long stamp; unsigned int acquired; unsigned short wounded; unsigned short is_wait_die;#ifdef DEBUG_WW_MUTEXES unsigned int done_acquire; struct ww_class *ww_class; void *contending_lock;#endif#ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; /** * @first_lock_dep_map: fake lockdep_map for first locked ww_mutex. * * lockdep requires the lockdep_map for the first locked ww_mutex * in a ww transaction to remain in memory until all ww_mutexes of * the transaction have been unlocked. Ensure this by keeping a * fake locked ww_mutex lockdep map between ww_acquire_init() and * ww_acquire_fini(). */ struct lockdep_map first_lock_dep_map;#endif#ifdef CONFIG_DEBUG_WW_MUTEX_SLOWPATH unsigned int deadlock_inject_interval; unsigned int deadlock_inject_countdown;#endif};
#define __WW_CLASS_INITIALIZER(ww_class, _is_wait_die) \ { .stamp = ATOMIC_LONG_INIT(0) \ , .acquire_name = #ww_class "_acquire" \ , .mutex_name = #ww_class "_mutex" \ , .is_wait_die = _is_wait_die }
#define DEFINE_WD_CLASS(classname) \ struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 1)
#define DEFINE_WW_CLASS(classname) \ struct ww_class classname = __WW_CLASS_INITIALIZER(classname, 0)
/** * 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. Static define macro for w/w mutex is not provided and this function * is the only way to properly initialize the w/w mutex. * * 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){ ww_mutex_base_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key); lock->ctx = NULL;#ifdef DEBUG_WW_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/die 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) __acquires(ctx) __no_context_analysis{ ctx->task = current; ctx->stamp = atomic_long_inc_return_relaxed(&ww_class->stamp); ctx->acquired = 0; ctx->wounded = false; ctx->is_wait_die = ww_class->is_wait_die;#ifdef DEBUG_WW_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); lockdep_init_map_wait(&ctx->first_lock_dep_map, ww_class->mutex_name, &ww_class->mutex_key, 0, LD_WAIT_SLEEP); mutex_acquire(&ctx->dep_map, 0, 0, _RET_IP_); mutex_acquire_nest(&ctx->first_lock_dep_map, 0, 0, &ctx->dep_map, _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) __must_hold(ctx){#ifdef DEBUG_WW_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) __releases(ctx) __no_context_analysis{#ifdef CONFIG_DEBUG_LOCK_ALLOC mutex_release(&ctx->first_lock_dep_map, _THIS_IP_); mutex_release(&ctx->dep_map, _THIS_IP_);#endif#ifdef DEBUG_WW_MUTEXES DEBUG_LOCKS_WARN_ON(ctx->acquired); if (!IS_ENABLED(CONFIG_PROVE_LOCKING)) /* * lockdep will normally handle this, * but fail without anyway */ ctx->done_acquire = 1;
if (!IS_ENABLED(CONFIG_DEBUG_LOCK_ALLOC)) /* ensure ww_acquire_fini will still fail if called twice */ ctx->acquired = ~0U;#endif}
/** * 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/die algorithm. If the lock isn't immediately available this function * will either sleep until it is (wait case). Or it selects the current context * for backing off by returning -EDEADLK (die 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 die 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. */extern int /* __must_check */ ww_mutex_lock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) __cond_acquires(0, lock) __must_hold(ctx);
/** * 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/die algorithm. If the lock isn't immediately available this function * will either sleep until it is (wait case). Or it selects the current context * for backing off by returning -EDEADLK (die 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 die 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. */extern int __must_check ww_mutex_lock_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) __cond_acquires(0, lock) __must_hold(ctx);
/** * 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 die 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 voidww_mutex_lock_slow(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) __acquires(lock) __must_hold(ctx) __no_context_analysis{ int ret;#ifdef DEBUG_WW_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 die 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_checkww_mutex_lock_slow_interruptible(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) __cond_acquires(0, lock) __must_hold(ctx){#ifdef DEBUG_WW_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) __releases(lock);
extern int __must_check ww_mutex_trylock(struct ww_mutex *lock, struct ww_acquire_ctx *ctx) __cond_acquires(true, lock) __must_hold(ctx);
/*** * 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) __must_not_hold(lock){#ifndef CONFIG_PREEMPT_RT mutex_destroy(&lock->base);#endif}
/** * 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 ww_mutex_base_is_locked(&lock->base);}
#endif