From: Davidlohr Bueso <dave@xxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxx Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/init_task.h | 5 +--- include/linux/rtmutex.h | 11 ++++----- include/linux/sched.h | 3 -- kernel/fork.c | 3 -- kernel/locking/rtmutex-debug.c | 2 - kernel/locking/rtmutex.c | 35 +++++++++--------------------- kernel/locking/rtmutex_common.h | 12 +++++----- 7 files changed, 27 insertions(+), 44 deletions(-) diff -puN include/linux/init_task.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching include/linux/init_task.h --- a/include/linux/init_task.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/include/linux/init_task.h @@ -175,9 +175,8 @@ extern struct cred init_cred; #ifdef CONFIG_RT_MUTEXES # define INIT_RT_MUTEXES(tsk) \ - .pi_waiters = RB_ROOT, \ - .pi_top_task = NULL, \ - .pi_waiters_leftmost = NULL, + .pi_waiters = RB_ROOT_CACHED, \ + .pi_top_task = NULL, #else # define INIT_RT_MUTEXES(tsk) #endif diff -puN include/linux/rtmutex.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching include/linux/rtmutex.h --- a/include/linux/rtmutex.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/include/linux/rtmutex.h @@ -22,18 +22,17 @@ extern int max_lock_depth; /* for sysctl * The rt_mutex structure * * @wait_lock: spinlock to protect the structure - * @waiters: rbtree root to enqueue waiters in priority order - * @waiters_leftmost: top waiter + * @waiters: rbtree root to enqueue waiters in priority order; + * caches top-waiter (leftmost node). * @owner: the mutex owner */ struct rt_mutex { raw_spinlock_t wait_lock; - struct rb_root waiters; - struct rb_node *waiters_leftmost; + struct rb_root_cached waiters; struct task_struct *owner; #ifdef CONFIG_DEBUG_RT_MUTEXES int save_state; - const char *name, *file; + const char *name, *file; int line; void *magic; #endif @@ -84,7 +83,7 @@ do { \ #define __RT_MUTEX_INITIALIZER(mutexname) \ { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \ - , .waiters = RB_ROOT \ + , .waiters = RB_ROOT_CACHED \ , .owner = NULL \ __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \ __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)} diff -puN include/linux/sched.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching include/linux/sched.h --- a/include/linux/sched.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/include/linux/sched.h @@ -812,8 +812,7 @@ struct task_struct { #ifdef CONFIG_RT_MUTEXES /* PI waiters blocked on a rt_mutex held by this task: */ - struct rb_root pi_waiters; - struct rb_node *pi_waiters_leftmost; + struct rb_root_cached pi_waiters; /* Updated under owner's pi_lock and rq lock */ struct task_struct *pi_top_task; /* Deadlock detection and priority inheritance handling: */ diff -puN kernel/fork.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching kernel/fork.c --- a/kernel/fork.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/kernel/fork.c @@ -1462,8 +1462,7 @@ static void rt_mutex_init_task(struct ta { raw_spin_lock_init(&p->pi_lock); #ifdef CONFIG_RT_MUTEXES - p->pi_waiters = RB_ROOT; - p->pi_waiters_leftmost = NULL; + p->pi_waiters = RB_ROOT_CACHED; p->pi_top_task = NULL; p->pi_blocked_on = NULL; #endif diff -puN kernel/locking/rtmutex-debug.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching kernel/locking/rtmutex-debug.c --- a/kernel/locking/rtmutex-debug.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/kernel/locking/rtmutex-debug.c @@ -58,7 +58,7 @@ static void printk_lock(struct rt_mutex void rt_mutex_debug_task_free(struct task_struct *task) { - DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters)); + DEBUG_LOCKS_WARN_ON(!RB_EMPTY_ROOT(&task->pi_waiters.rb_root)); DEBUG_LOCKS_WARN_ON(task->pi_blocked_on); } diff -puN kernel/locking/rtmutex.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching kernel/locking/rtmutex.c --- a/kernel/locking/rtmutex.c~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/kernel/locking/rtmutex.c @@ -271,10 +271,10 @@ rt_mutex_waiter_equal(struct rt_mutex_wa static void rt_mutex_enqueue(struct rt_mutex *lock, struct rt_mutex_waiter *waiter) { - struct rb_node **link = &lock->waiters.rb_node; + struct rb_node **link = &lock->waiters.rb_root.rb_node; struct rb_node *parent = NULL; struct rt_mutex_waiter *entry; - int leftmost = 1; + bool leftmost = true; while (*link) { parent = *link; @@ -283,15 +283,12 @@ rt_mutex_enqueue(struct rt_mutex *lock, link = &parent->rb_left; } else { link = &parent->rb_right; - leftmost = 0; + leftmost = false; } } - if (leftmost) - lock->waiters_leftmost = &waiter->tree_entry; - rb_link_node(&waiter->tree_entry, parent, link); - rb_insert_color(&waiter->tree_entry, &lock->waiters); + rb_insert_color_cached(&waiter->tree_entry, &lock->waiters, leftmost); } static void @@ -300,20 +297,17 @@ rt_mutex_dequeue(struct rt_mutex *lock, if (RB_EMPTY_NODE(&waiter->tree_entry)) return; - if (lock->waiters_leftmost == &waiter->tree_entry) - lock->waiters_leftmost = rb_next(&waiter->tree_entry); - - rb_erase(&waiter->tree_entry, &lock->waiters); + rb_erase_cached(&waiter->tree_entry, &lock->waiters); RB_CLEAR_NODE(&waiter->tree_entry); } static void rt_mutex_enqueue_pi(struct task_struct *task, struct rt_mutex_waiter *waiter) { - struct rb_node **link = &task->pi_waiters.rb_node; + struct rb_node **link = &task->pi_waiters.rb_root.rb_node; struct rb_node *parent = NULL; struct rt_mutex_waiter *entry; - int leftmost = 1; + bool leftmost = true; while (*link) { parent = *link; @@ -322,15 +316,12 @@ rt_mutex_enqueue_pi(struct task_struct * link = &parent->rb_left; } else { link = &parent->rb_right; - leftmost = 0; + leftmost = false; } } - if (leftmost) - task->pi_waiters_leftmost = &waiter->pi_tree_entry; - rb_link_node(&waiter->pi_tree_entry, parent, link); - rb_insert_color(&waiter->pi_tree_entry, &task->pi_waiters); + rb_insert_color_cached(&waiter->pi_tree_entry, &task->pi_waiters, leftmost); } static void @@ -339,10 +330,7 @@ rt_mutex_dequeue_pi(struct task_struct * if (RB_EMPTY_NODE(&waiter->pi_tree_entry)) return; - if (task->pi_waiters_leftmost == &waiter->pi_tree_entry) - task->pi_waiters_leftmost = rb_next(&waiter->pi_tree_entry); - - rb_erase(&waiter->pi_tree_entry, &task->pi_waiters); + rb_erase_cached(&waiter->pi_tree_entry, &task->pi_waiters); RB_CLEAR_NODE(&waiter->pi_tree_entry); } @@ -1657,8 +1645,7 @@ void __rt_mutex_init(struct rt_mutex *lo { lock->owner = NULL; raw_spin_lock_init(&lock->wait_lock); - lock->waiters = RB_ROOT; - lock->waiters_leftmost = NULL; + lock->waiters = RB_ROOT_CACHED; if (name && key) debug_rt_mutex_init(lock, name, key); diff -puN kernel/locking/rtmutex_common.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching kernel/locking/rtmutex_common.h --- a/kernel/locking/rtmutex_common.h~locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching +++ a/kernel/locking/rtmutex_common.h @@ -45,7 +45,7 @@ struct rt_mutex_waiter { static inline int rt_mutex_has_waiters(struct rt_mutex *lock) { - return !RB_EMPTY_ROOT(&lock->waiters); + return !RB_EMPTY_ROOT(&lock->waiters.rb_root); } static inline struct rt_mutex_waiter * @@ -53,8 +53,8 @@ rt_mutex_top_waiter(struct rt_mutex *loc { struct rt_mutex_waiter *w; - w = rb_entry(lock->waiters_leftmost, struct rt_mutex_waiter, - tree_entry); + w = rb_entry(lock->waiters.rb_leftmost, + struct rt_mutex_waiter, tree_entry); BUG_ON(w->lock != lock); return w; @@ -62,14 +62,14 @@ rt_mutex_top_waiter(struct rt_mutex *loc static inline int task_has_pi_waiters(struct task_struct *p) { - return !RB_EMPTY_ROOT(&p->pi_waiters); + return !RB_EMPTY_ROOT(&p->pi_waiters.rb_root); } static inline struct rt_mutex_waiter * task_top_pi_waiter(struct task_struct *p) { - return rb_entry(p->pi_waiters_leftmost, struct rt_mutex_waiter, - pi_tree_entry); + return rb_entry(p->pi_waiters.rb_leftmost, + struct rt_mutex_waiter, pi_tree_entry); } #else _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
