* state.
*/
-static void
+void
rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner,
unsigned long mask)
{
clear_rt_mutex_waiters(lock);
}
-/*
- * We can speed up the acquire/release, if the architecture
- * supports cmpxchg and if there's no debugging state to be set up
- */
-#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
-# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c)
-static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
-{
- unsigned long owner, *p = (unsigned long *) &lock->owner;
-
- do {
- owner = *p;
- } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
-}
-#else
-# define rt_mutex_cmpxchg(l,c,n) (0)
-static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
-{
- lock->owner = (struct task_struct *)
- ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
-}
-#endif
-
/*
* Calculate task priority from the waiter list priority
*
*
* This can be both boosting and unboosting. task->pi_lock must be held.
*/
-static void __rt_mutex_adjust_prio(struct task_struct *task)
+void __rt_mutex_adjust_prio(struct task_struct *task)
{
int prio = rt_mutex_getprio(task);
* Decreases task's usage by one - may thus free the task.
* Returns 0 or -EDEADLK.
*/
-static int rt_mutex_adjust_prio_chain(struct task_struct *task,
- int deadlock_detect,
- struct rt_mutex *orig_lock,
- struct rt_mutex_waiter *orig_waiter,
- struct task_struct *top_task)
+int rt_mutex_adjust_prio_chain(struct task_struct *task,
+ int deadlock_detect,
+ struct rt_mutex *orig_lock,
+ struct rt_mutex_waiter *orig_waiter,
+ struct task_struct *top_task)
{
struct rt_mutex *lock;
struct rt_mutex_waiter *waiter, *top_waiter = orig_waiter;
if (!waiter || !waiter->task)
goto out_unlock_pi;
+ /*
+ * Check the orig_waiter state. After we dropped the locks,
+ * the previous owner of the lock might have released the lock
+ * and made us the pending owner:
+ */
+ if (orig_waiter && !orig_waiter->task)
+ goto out_unlock_pi;
+
+ /*
+ * Drop out, when the task has no waiters. Note,
+ * top_waiter can be NULL, when we are in the deboosting
+ * mode!
+ */
if (top_waiter && (!task_has_pi_waiters(task) ||
top_waiter != task_top_pi_waiter(task)))
goto out_unlock_pi;
/* Grab the next task */
task = rt_mutex_owner(lock);
+ get_task_struct(task);
spin_lock_irqsave(&task->pi_lock, flags);
if (waiter == rt_mutex_top_waiter(lock)) {
__rt_mutex_adjust_prio(task);
}
- get_task_struct(task);
spin_unlock_irqrestore(&task->pi_lock, flags);
top_waiter = rt_mutex_top_waiter(lock);
struct task_struct *owner = rt_mutex_owner(lock);
struct rt_mutex_waiter *top_waiter = waiter;
unsigned long flags;
- int boost = 0, res;
+ int chain_walk = 0, res;
spin_lock_irqsave(¤t->pi_lock, flags);
__rt_mutex_adjust_prio(current);
plist_add(&waiter->pi_list_entry, &owner->pi_waiters);
__rt_mutex_adjust_prio(owner);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
- spin_unlock_irqrestore(&owner->pi_lock, flags);
- }
- else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) {
- spin_lock_irqsave(&owner->pi_lock, flags);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
- if (!boost)
+ else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock))
+ chain_walk = 1;
+
+ if (!chain_walk)
return 0;
+ /*
+ * The owner can't disappear while holding a lock,
+ * so the owner struct is protected by wait_lock.
+ * Gets dropped in rt_mutex_adjust_prio_chain()!
+ */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
res = rt_mutex_adjust_prio_chain(owner, detect_deadlock, lock, waiter,
*
* Must be called with lock->wait_lock held
*/
-static void remove_waiter(struct rt_mutex *lock,
- struct rt_mutex_waiter *waiter)
+void remove_waiter(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter)
{
int first = (waiter == rt_mutex_top_waiter(lock));
struct task_struct *owner = rt_mutex_owner(lock);
unsigned long flags;
- int boost = 0;
+ int chain_walk = 0;
spin_lock_irqsave(¤t->pi_lock, flags);
plist_del(&waiter->list_entry, &lock->wait_list);
}
__rt_mutex_adjust_prio(owner);
- if (owner->pi_blocked_on) {
- boost = 1;
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(owner);
- }
+ if (owner->pi_blocked_on)
+ chain_walk = 1;
+
spin_unlock_irqrestore(&owner->pi_lock, flags);
}
WARN_ON(!plist_node_empty(&waiter->pi_list_entry));
- if (!boost)
+ if (!chain_walk)
return;
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(owner);
+
spin_unlock(&lock->wait_lock);
rt_mutex_adjust_prio_chain(owner, 0, lock, NULL, current);
return;
}
- /* gets dropped in rt_mutex_adjust_prio_chain()! */
- get_task_struct(task);
spin_unlock_irqrestore(&task->pi_lock, flags);
+ /* gets dropped in rt_mutex_adjust_prio_chain()! */
+ get_task_struct(task);
rt_mutex_adjust_prio_chain(task, 0, NULL, NULL, task);
}
/* Setup the timer, when timeout != NULL */
if (unlikely(timeout))
hrtimer_start(&timeout->timer, timeout->timer.expires,
- HRTIMER_ABS);
+ HRTIMER_MODE_ABS);
for (;;) {
/* Try to acquire the lock: */
* all over without going into schedule to try
* to get the lock now:
*/
- if (unlikely(!waiter.task))
+ if (unlikely(!waiter.task)) {
+ /*
+ * Reset the return value. We might
+ * have returned with -EDEADLK and the
+ * owner released the lock while we
+ * were walking the pi chain.
+ */
+ ret = 0;
continue;
-
+ }
if (unlikely(ret))
break;
}
projects / linux-drm-fsl-dcu.git / blobdiff