locking/rtmutex: replace top-waiter and pi_waiters leftmost caching
... with the generic rbtree flavor instead. No changes in semantics whatsoever. Link: http://lkml.kernel.org/r/20170719014603.19029-10-dave@stgolabs.net Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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a23ba907d5
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@ -175,9 +175,8 @@ extern struct cred init_cred;
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#ifdef CONFIG_RT_MUTEXES
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# define INIT_RT_MUTEXES(tsk) \
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.pi_waiters = RB_ROOT, \
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.pi_top_task = NULL, \
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.pi_waiters_leftmost = NULL,
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.pi_waiters = RB_ROOT_CACHED, \
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.pi_top_task = NULL,
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#else
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# define INIT_RT_MUTEXES(tsk)
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#endif
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@ -22,18 +22,17 @@ extern int max_lock_depth; /* for sysctl */
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* The rt_mutex structure
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*
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* @wait_lock: spinlock to protect the structure
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* @waiters: rbtree root to enqueue waiters in priority order
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* @waiters_leftmost: top waiter
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* @waiters: rbtree root to enqueue waiters in priority order;
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* caches top-waiter (leftmost node).
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* @owner: the mutex owner
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*/
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struct rt_mutex {
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raw_spinlock_t wait_lock;
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struct rb_root waiters;
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struct rb_node *waiters_leftmost;
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struct rb_root_cached waiters;
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struct task_struct *owner;
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#ifdef CONFIG_DEBUG_RT_MUTEXES
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int save_state;
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const char *name, *file;
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const char *name, *file;
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int line;
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void *magic;
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#endif
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@ -84,7 +83,7 @@ do { \
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#define __RT_MUTEX_INITIALIZER(mutexname) \
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{ .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
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, .waiters = RB_ROOT \
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, .waiters = RB_ROOT_CACHED \
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, .owner = NULL \
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__DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
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__DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
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@ -812,8 +812,7 @@ struct task_struct {
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#ifdef CONFIG_RT_MUTEXES
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/* PI waiters blocked on a rt_mutex held by this task: */
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struct rb_root pi_waiters;
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struct rb_node *pi_waiters_leftmost;
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struct rb_root_cached pi_waiters;
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/* Updated under owner's pi_lock and rq lock */
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struct task_struct *pi_top_task;
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/* Deadlock detection and priority inheritance handling: */
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@ -1462,8 +1462,7 @@ static void rt_mutex_init_task(struct task_struct *p)
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{
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raw_spin_lock_init(&p->pi_lock);
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#ifdef CONFIG_RT_MUTEXES
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p->pi_waiters = RB_ROOT;
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p->pi_waiters_leftmost = NULL;
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p->pi_waiters = RB_ROOT_CACHED;
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p->pi_top_task = NULL;
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p->pi_blocked_on = NULL;
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#endif
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@ -58,7 +58,7 @@ static void printk_lock(struct rt_mutex *lock, int print_owner)
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void rt_mutex_debug_task_free(struct task_struct *task)
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{
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DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters));
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DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root));
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DEBUG_LOCKS_WARN_ON(task->pi_blocked_on);
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}
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@ -271,10 +271,10 @@ rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
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static void
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rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
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{
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struct rb_node **link = &lock->waiters.rb_node;
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struct rb_node **link = &lock->waiters.rb_root.rb_node;
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struct rb_node *parent = NULL;
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struct rt_mutex_waiter *entry;
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int leftmost = 1;
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bool leftmost = true;
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while (*link) {
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parent = *link;
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@ -283,15 +283,12 @@ rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
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link = &parent->rb_left;
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} else {
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link = &parent->rb_right;
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leftmost = 0;
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leftmost = false;
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}
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}
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if (leftmost)
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lock->waiters_leftmost = &waiter->tree_entry;
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rb_link_node(&waiter->tree_entry, parent, link);
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rb_insert_color(&waiter->tree_entry, &lock->waiters);
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rb_insert_color_cached(&waiter->tree_entry, &lock->waiters, leftmost);
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}
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static void
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@ -300,20 +297,17 @@ rt_mutex_dequeue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter)
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if (RB_EMPTY_NODE(&waiter->tree_entry))
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return;
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if (lock->waiters_leftmost == &waiter->tree_entry)
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lock->waiters_leftmost = rb_next(&waiter->tree_entry);
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rb_erase(&waiter->tree_entry, &lock->waiters);
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rb_erase_cached(&waiter->tree_entry, &lock->waiters);
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RB_CLEAR_NODE(&waiter->tree_entry);
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}
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static void
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rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
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{
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struct rb_node **link = &task->pi_waiters.rb_node;
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struct rb_node **link = &task->pi_waiters.rb_root.rb_node;
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struct rb_node *parent = NULL;
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struct rt_mutex_waiter *entry;
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int leftmost = 1;
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bool leftmost = true;
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while (*link) {
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parent = *link;
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@ -322,15 +316,12 @@ rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
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link = &parent->rb_left;
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} else {
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link = &parent->rb_right;
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leftmost = 0;
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leftmost = false;
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}
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}
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if (leftmost)
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task->pi_waiters_leftmost = &waiter->pi_tree_entry;
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rb_link_node(&waiter->pi_tree_entry, parent, link);
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rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters);
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rb_insert_color_cached(&waiter->pi_tree_entry, &task->pi_waiters, leftmost);
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}
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static void
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@ -339,10 +330,7 @@ rt_mutex_dequeue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter)
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if (RB_EMPTY_NODE(&waiter->pi_tree_entry))
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return;
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if (task->pi_waiters_leftmost == &waiter->pi_tree_entry)
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task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry);
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rb_erase(&waiter->pi_tree_entry, &task->pi_waiters);
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rb_erase_cached(&waiter->pi_tree_entry, &task->pi_waiters);
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RB_CLEAR_NODE(&waiter->pi_tree_entry);
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}
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@ -1657,8 +1645,7 @@ void __rt_mutex_init(struct rt_mutex *lock, const char *name,
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{
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lock->owner = NULL;
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raw_spin_lock_init(&lock->wait_lock);
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lock->waiters = RB_ROOT;
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lock->waiters_leftmost = NULL;
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lock->waiters = RB_ROOT_CACHED;
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if (name && key)
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debug_rt_mutex_init(lock, name, key);
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@ -45,7 +45,7 @@ struct rt_mutex_waiter {
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static inline int rt_mutex_has_waiters(struct rt_mutex *lock)
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{
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return !RB_EMPTY_ROOT(&lock->waiters);
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return !RB_EMPTY_ROOT(&lock->waiters.rb_root);
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}
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static inline struct rt_mutex_waiter *
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@ -53,8 +53,8 @@ rt_mutex_top_waiter(struct rt_mutex *lock)
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{
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struct rt_mutex_waiter *w;
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w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter,
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tree_entry);
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w = rb_entry(lock->waiters.rb_leftmost,
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struct rt_mutex_waiter, tree_entry);
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BUG_ON(w->lock != lock);
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return w;
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@ -62,14 +62,14 @@ rt_mutex_top_waiter(struct rt_mutex *lock)
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static inline int task_has_pi_waiters(struct task_struct *p)
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{
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return !RB_EMPTY_ROOT(&p->pi_waiters);
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return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root);
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}
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static inline struct rt_mutex_waiter *
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task_top_pi_waiter(struct task_struct *p)
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{
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return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter,
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pi_tree_entry);
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return rb_entry(p->pi_waiters.rb_leftmost,
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struct rt_mutex_waiter, pi_tree_entry);
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}
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#else
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