makes it easier to port ttm over..
Signed-off-by: Maarten Lankhorst <maarten.lankhorst at canonical.com>
---
include/linux/mutex.h | 86 +++++++++++++-
kernel/mutex.c | 317 +++++++++++++++++++++++++++++++++++++++++++++++---
2 files changed, 387 insertions(+), 16 deletions(-)
diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 9121595..602c247 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -62,6 +62,11 @@ struct mutex {
#endif
};
+struct ticket_mutex {
+ struct mutex base;
+ atomic_long_t reservation_id;
+};
+
/*
* This is the control structure for tasks blocked on mutex,
* which resides on the blocked task's kernel stack:
@@ -109,12 +114,24 @@ static inline void mutex_destroy(struct mutex *lock) {}
__DEBUG_MUTEX_INITIALIZER(lockname) \
__DEP_MAP_MUTEX_INITIALIZER(lockname) }
+#define __TICKET_MUTEX_INITIALIZER(lockname) \
+ { .base = __MUTEX_INITIALIZER(lockname) \
+ , .reservation_id = ATOMIC_LONG_INIT(0) }
+
#define DEFINE_MUTEX(mutexname) \
struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
extern void __mutex_init(struct mutex *lock, const char *name,
struct lock_class_key *key);
+static inline void __ticket_mutex_init(struct ticket_mutex *lock,
+ const char *name,
+ struct lock_class_key *key)
+{
+ __mutex_init(&lock->base, name, key);
+ atomic_long_set(&lock->reservation_id, 0);
+}
+
/**
* mutex_is_locked - is the mutex locked
* @lock: the mutex to be queried
@@ -133,26 +150,91 @@ static inline int mutex_is_locked(struct mutex *lock)
#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map
*nest_lock);
+
extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
unsigned int subclass);
extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
unsigned int subclass);
+extern int __must_check _mutex_reserve_lock(struct ticket_mutex *lock,
+ struct lockdep_map *nest_lock,
+ unsigned long reservation_id);
+
+extern int __must_check _mutex_reserve_lock_interruptible(struct ticket_mutex
*,
+ struct lockdep_map *nest_lock,
+ unsigned long reservation_id);
+
+extern void _mutex_reserve_lock_slow(struct ticket_mutex *lock,
+ struct lockdep_map *nest_lock,
+ unsigned long reservation_id);
+
+extern int __must_check _mutex_reserve_lock_intr_slow(struct ticket_mutex *,
+ struct lockdep_map *nest_lock,
+ unsigned long reservation_id);
+
#define mutex_lock(lock) mutex_lock_nested(lock, 0)
#define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
#define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
#define mutex_lock_nest_lock(lock, nest_lock) \
do { \
- typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map); \
} while (0)
+#define mutex_reserve_lock(lock, nest_lock, reservation_id) \
+({ \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _mutex_reserve_lock(lock, &(nest_lock)->dep_map, reservation_id);
\
+})
+
+#define mutex_reserve_lock_interruptible(lock, nest_lock, reservation_id)
\
+({ \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _mutex_reserve_lock_interruptible(lock, &(nest_lock)->dep_map, \
+ reservation_id); \
+})
+
+#define mutex_reserve_lock_slow(lock, nest_lock, reservation_id) \
+do { \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _mutex_reserve_lock_slow(lock, &(nest_lock)->dep_map, reservation_id);
\
+} while (0)
+
+#define mutex_reserve_lock_intr_slow(lock, nest_lock, reservation_id) \
+({ \
+ typecheck(struct lockdep_map *, &(nest_lock)->dep_map); \
+ _mutex_reserve_lock_intr_slow(lock, &(nest_lock)->dep_map, \
+ reservation_id); \
+})
+
#else
extern void mutex_lock(struct mutex *lock);
extern int __must_check mutex_lock_interruptible(struct mutex *lock);
extern int __must_check mutex_lock_killable(struct mutex *lock);
+extern int __must_check _mutex_reserve_lock(struct ticket_mutex *lock,
+ unsigned long reservation_id);
+extern int __must_check _mutex_reserve_lock_interruptible(struct ticket_mutex
*,
+ unsigned long reservation_id);
+
+extern void _mutex_reserve_lock_slow(struct ticket_mutex *lock,
+ unsigned long reservation_id);
+extern int __must_check _mutex_reserve_lock_intr_slow(struct ticket_mutex *,
+ unsigned long reservation_id);
+
+#define mutex_reserve_lock(lock, nest_lock, reservation_id) \
+ _mutex_reserve_lock(lock, reservation_id)
+
+#define mutex_reserve_lock_interruptible(lock, nest_lock, reservation_id)
\
+ _mutex_reserve_lock_interruptible(lock, reservation_id)
+
+#define mutex_reserve_lock_slow(lock, nest_lock, reservation_id) \
+ _mutex_reserve_lock_slow(lock, reservation_id)
+
+#define mutex_reserve_lock_intr_slow(lock, nest_lock, reservation_id) \
+ _mutex_reserve_lock_intr_slow(lock, reservation_id)
+
# define mutex_lock_nested(lock, subclass) mutex_lock(lock)
# define mutex_lock_interruptible_nested(lock, subclass)
mutex_lock_interruptible(lock)
# define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
@@ -167,6 +249,8 @@ extern int __must_check mutex_lock_killable(struct mutex
*lock);
*/
extern int mutex_trylock(struct mutex *lock);
extern void mutex_unlock(struct mutex *lock);
+extern void mutex_unreserve_unlock(struct ticket_mutex *lock);
+
extern int atomic_dec_and_mutex_lock(atomic_t *cnt, struct mutex *lock);
#ifndef CONFIG_HAVE_ARCH_MUTEX_CPU_RELAX
diff --git a/kernel/mutex.c b/kernel/mutex.c
index a307cc9..8282729 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -126,16 +126,119 @@ void __sched mutex_unlock(struct mutex *lock)
EXPORT_SYMBOL(mutex_unlock);
+/**
+ * mutex_unreserve_unlock - release the mutex
+ * @lock: the mutex to be released
+ *
+ * Unlock a mutex that has been locked by this task previously
+ * with _mutex_reserve_lock*.
+ *
+ * This function must not be used in interrupt context. Unlocking
+ * of a not locked mutex is not allowed.
+ */
+void __sched mutex_unreserve_unlock(struct ticket_mutex *lock)
+{
+ /*
+ * mark mutex as no longer part of a reservation, next
+ * locker can set this again
+ */
+ atomic_long_set(&lock->reservation_id, 0);
+
+ /*
+ * The unlocking fastpath is the 0->1 transition from 'locked'
+ * into 'unlocked' state:
+ */
+#ifndef CONFIG_DEBUG_MUTEXES
+ /*
+ * When debugging is enabled we must not clear the owner before time,
+ * the slow path will always be taken, and that clears the owner field
+ * after verifying that it was indeed current.
+ */
+ mutex_clear_owner(&lock->base);
+#endif
+ __mutex_fastpath_unlock(&lock->base.count, __mutex_unlock_slowpath);
+}
+EXPORT_SYMBOL(mutex_unreserve_unlock);
+
+static inline int __sched
+__mutex_lock_check_reserve(struct mutex *lock, unsigned long reservation_id)
+{
+ struct ticket_mutex *m = container_of(lock, struct ticket_mutex, base);
+ unsigned long cur_id;
+
+ cur_id = atomic_long_read(&m->reservation_id);
+ if (!cur_id)
+ return 0;
+
+ if (unlikely(reservation_id == cur_id))
+ return -EDEADLK;
+
+ if (unlikely(reservation_id - cur_id <= LONG_MAX))
+ return -EAGAIN;
+
+ return 0;
+}
+
+/*
+ * after acquiring lock with fastpath or when we lost out in contested
+ * slowpath, set reservation_id and wake up any waiters so they can recheck.
+ */
+static __always_inline void
+mutex_set_reservation_fastpath(struct ticket_mutex *lock,
+ unsigned long reservation_id, bool check_res)
+{
+ unsigned long flags;
+ struct mutex_waiter *cur;
+
+ if (check_res || config_enabled(CONFIG_DEBUG_LOCK_ALLOC)) {
+ unsigned long cur_id;
+
+ cur_id = atomic_long_xchg(&lock->reservation_id,
+ reservation_id);
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ if (check_res)
+ DEBUG_LOCKS_WARN_ON(cur_id &&
+ cur_id != reservation_id);
+ else
+ DEBUG_LOCKS_WARN_ON(cur_id);
+ lockdep_assert_held(&lock->base);
+#endif
+
+ if (unlikely(cur_id == reservation_id))
+ return;
+ } else
+ atomic_long_set(&lock->reservation_id, reservation_id);
+
+ /*
+ * Check if lock is contended, if not there is nobody to wake up
+ */
+ if (likely(atomic_read(&lock->base.count) == 0))
+ return;
+
+ /*
+ * Uh oh, we raced in fastpath, wake up everyone in this case,
+ * so they can see the new reservation_id
+ */
+ spin_lock_mutex(&lock->base.wait_lock, flags);
+ list_for_each_entry(cur, &lock->base.wait_list, list) {
+ debug_mutex_wake_waiter(&lock->base, cur);
+ wake_up_process(cur->task);
+ }
+ spin_unlock_mutex(&lock->base.wait_lock, flags);
+}
+
/*
* Lock a mutex (possibly interruptible), slowpath:
*/
static inline int __sched
__mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
- struct lockdep_map *nest_lock, unsigned long ip)
+ struct lockdep_map *nest_lock, unsigned long ip,
+ unsigned long reservation_id, bool res_slow)
{
struct task_struct *task = current;
struct mutex_waiter waiter;
unsigned long flags;
+ int ret;
preempt_disable();
mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
@@ -162,6 +265,12 @@ __mutex_lock_common(struct mutex *lock, long state,
unsigned int subclass,
for (;;) {
struct task_struct *owner;
+ if (!__builtin_constant_p(reservation_id) && !res_slow) {
+ ret = __mutex_lock_check_reserve(lock, reservation_id);
+ if (ret)
+ goto err_nowait;
+ }
+
/*
* If there's an owner, wait for it to either
* release the lock or go to sleep.
@@ -172,6 +281,13 @@ __mutex_lock_common(struct mutex *lock, long state,
unsigned int subclass,
if (atomic_cmpxchg(&lock->count, 1, 0) == 1) {
lock_acquired(&lock->dep_map, ip);
+ if (res_slow) {
+ struct ticket_mutex *m;
+ m = container_of(lock, struct ticket_mutex,
base);
+
+ mutex_set_reservation_fastpath(m,
reservation_id, false);
+ }
+
mutex_set_owner(lock);
preempt_enable();
return 0;
@@ -227,15 +343,16 @@ __mutex_lock_common(struct mutex *lock, long state,
unsigned int subclass,
* TASK_UNINTERRUPTIBLE case.)
*/
if (unlikely(signal_pending_state(state, task))) {
- mutex_remove_waiter(lock, &waiter,
- task_thread_info(task));
- mutex_release(&lock->dep_map, 1, ip);
- spin_unlock_mutex(&lock->wait_lock, flags);
+ ret = -EINTR;
+ goto err;
+ }
- debug_mutex_free_waiter(&waiter);
- preempt_enable();
- return -EINTR;
+ if (!__builtin_constant_p(reservation_id) && !res_slow) {
+ ret = __mutex_lock_check_reserve(lock, reservation_id);
+ if (ret)
+ goto err;
}
+
__set_task_state(task, state);
/* didn't get the lock, go to sleep: */
@@ -250,6 +367,28 @@ done:
mutex_remove_waiter(lock, &waiter, current_thread_info());
mutex_set_owner(lock);
+ if (!__builtin_constant_p(reservation_id)) {
+ struct ticket_mutex *m;
+ struct mutex_waiter *cur;
+ /*
+ * this should get optimized out for the common case,
+ * and is only important for _mutex_reserve_lock
+ */
+
+ m = container_of(lock, struct ticket_mutex, base);
+ atomic_long_set(&m->reservation_id, reservation_id);
+
+ /*
+ * give any possible sleeping processes the chance to wake up,
+ * so they can recheck if they have to back off from
+ * reservations
+ */
+ list_for_each_entry(cur, &lock->wait_list, list) {
+ debug_mutex_wake_waiter(lock, cur);
+ wake_up_process(cur->task);
+ }
+ }
+
/* set it to 0 if there are no waiters left: */
if (likely(list_empty(&lock->wait_list)))
atomic_set(&lock->count, 0);
@@ -260,6 +399,19 @@ done:
preempt_enable();
return 0;
+
+err:
+ mutex_remove_waiter(lock, &waiter, task_thread_info(task));
+ spin_unlock_mutex(&lock->wait_lock, flags);
+ debug_mutex_free_waiter(&waiter);
+
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
+err_nowait:
+#endif
+ mutex_release(&lock->dep_map, 1, ip);
+
+ preempt_enable();
+ return ret;
}
#ifdef CONFIG_DEBUG_LOCK_ALLOC
@@ -267,7 +419,8 @@ void __sched
mutex_lock_nested(struct mutex *lock, unsigned int subclass)
{
might_sleep();
- __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL,
_RET_IP_);
+ __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+ subclass, NULL, _RET_IP_, 0, 0);
}
EXPORT_SYMBOL_GPL(mutex_lock_nested);
@@ -276,7 +429,8 @@ void __sched
_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
{
might_sleep();
- __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
+ __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE,
+ 0, nest, _RET_IP_, 0, 0);
}
EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
@@ -285,7 +439,8 @@ int __sched
mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
{
might_sleep();
- return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL,
_RET_IP_);
+ return __mutex_lock_common(lock, TASK_KILLABLE,
+ subclass, NULL, _RET_IP_, 0, 0);
}
EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
@@ -294,10 +449,63 @@ mutex_lock_interruptible_nested(struct mutex *lock,
unsigned int subclass)
{
might_sleep();
return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,
- subclass, NULL, _RET_IP_);
+ subclass, NULL, _RET_IP_, 0, 0);
}
EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
+
+int __sched
+_mutex_reserve_lock(struct ticket_mutex *lock, struct lockdep_map *nest,
+ unsigned long reservation_id)
+{
+ DEBUG_LOCKS_WARN_ON(!reservation_id);
+
+ might_sleep();
+ return __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
+ 0, nest, _RET_IP_, reservation_id, 0);
+}
+EXPORT_SYMBOL_GPL(_mutex_reserve_lock);
+
+
+int __sched
+_mutex_reserve_lock_interruptible(struct ticket_mutex *lock,
+ struct lockdep_map *nest,
+ unsigned long reservation_id)
+{
+ DEBUG_LOCKS_WARN_ON(!reservation_id);
+
+ might_sleep();
+ return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
+ 0, nest, _RET_IP_, reservation_id, 0);
+}
+EXPORT_SYMBOL_GPL(_mutex_reserve_lock_interruptible);
+
+void __sched
+_mutex_reserve_lock_slow(struct ticket_mutex *lock, struct lockdep_map *nest,
+ unsigned long reservation_id)
+{
+ DEBUG_LOCKS_WARN_ON(!reservation_id);
+
+ might_sleep();
+ __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE, 0,
+ nest, _RET_IP_, reservation_id, 1);
+}
+EXPORT_SYMBOL_GPL(_mutex_reserve_lock_slow);
+
+int __sched
+_mutex_reserve_lock_intr_slow(struct ticket_mutex *lock,
+ struct lockdep_map *nest,
+ unsigned long reservation_id)
+{
+ DEBUG_LOCKS_WARN_ON(!reservation_id);
+
+ might_sleep();
+ return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE, 0,
+ nest, _RET_IP_, reservation_id, 1);
+}
+EXPORT_SYMBOL_GPL(_mutex_reserve_lock_intr_slow);
+
+
#endif
/*
@@ -400,7 +608,8 @@ __mutex_lock_slowpath(atomic_t *lock_count)
{
struct mutex *lock = container_of(lock_count, struct mutex, count);
- __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
+ __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,
+ NULL, _RET_IP_, 0, 0);
}
static noinline int __sched
@@ -408,7 +617,8 @@ __mutex_lock_killable_slowpath(atomic_t *lock_count)
{
struct mutex *lock = container_of(lock_count, struct mutex, count);
- return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
+ return __mutex_lock_common(lock, TASK_KILLABLE, 0,
+ NULL, _RET_IP_, 0, 0);
}
static noinline int __sched
@@ -416,8 +626,28 @@ __mutex_lock_interruptible_slowpath(atomic_t *lock_count)
{
struct mutex *lock = container_of(lock_count, struct mutex, count);
- return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
+ return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,
+ NULL, _RET_IP_, 0, 0);
+}
+
+static noinline int __sched
+__mutex_lock_reserve_slowpath(atomic_t *lock_count, void *rid)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+ return __mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0,
+ NULL, _RET_IP_, (unsigned long)rid, 0);
+}
+
+static noinline int __sched
+__mutex_lock_interruptible_reserve_slowpath(atomic_t *lock_count, void *rid)
+{
+ struct mutex *lock = container_of(lock_count, struct mutex, count);
+
+ return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0,
+ NULL, _RET_IP_, (unsigned long)rid, 0);
}
+
#endif
/*
@@ -473,6 +703,63 @@ int __sched mutex_trylock(struct mutex *lock)
}
EXPORT_SYMBOL(mutex_trylock);
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
+int __sched
+_mutex_reserve_lock(struct ticket_mutex *lock, unsigned long rid)
+{
+ int ret;
+
+ might_sleep();
+
+ ret = __mutex_fastpath_lock_retval_arg(&lock->base.count, (void *)rid,
+ __mutex_lock_reserve_slowpath);
+
+ if (!ret) {
+ mutex_set_reservation_fastpath(lock, rid, true);
+ mutex_set_owner(&lock->base);
+ }
+ return ret;
+}
+EXPORT_SYMBOL(_mutex_reserve_lock);
+
+int __sched
+_mutex_reserve_lock_interruptible(struct ticket_mutex *lock, unsigned long rid)
+{
+ int ret;
+
+ might_sleep();
+
+ ret = __mutex_fastpath_lock_retval_arg(&lock->base.count, (void *)rid,
+ __mutex_lock_interruptible_reserve_slowpath);
+
+ if (!ret) {
+ mutex_set_reservation_fastpath(lock, rid, true);
+ mutex_set_owner(&lock->base);
+ }
+ return ret;
+}
+EXPORT_SYMBOL(_mutex_reserve_lock_interruptible);
+
+void __sched
+_mutex_reserve_lock_slow(struct ticket_mutex *lock, unsigned long rid)
+{
+ might_sleep();
+ __mutex_lock_common(&lock->base, TASK_UNINTERRUPTIBLE,
+ 0, NULL, _RET_IP_, rid, 1);
+}
+EXPORT_SYMBOL(_mutex_reserve_lock_slow);
+
+int __sched
+_mutex_reserve_lock_intr_slow(struct ticket_mutex *lock, unsigned long rid)
+{
+ might_sleep();
+ return __mutex_lock_common(&lock->base, TASK_INTERRUPTIBLE,
+ 0, NULL, _RET_IP_, rid, 1);
+}
+EXPORT_SYMBOL(_mutex_reserve_lock_intr_slow);
+
+#endif
+
/**
* atomic_dec_and_mutex_lock - return holding mutex if we dec to 0
* @cnt: the atomic which we are to dec
--
1.8.0.3
