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authorDavidlohr Bueso <dave@stgolabs.net>2017-09-08 16:15:01 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-08 18:26:49 -0700
commita23ba907d5e65d6aeea3e59c82fda9cd206a7aad (patch)
treea0bd42b27596cf758517fa004d1d8681a7eef932 /kernel
parent2161573ecd6931565936cb66793b2d2bf805c088 (diff)
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c3
-rw-r--r--kernel/locking/rtmutex-debug.c2
-rw-r--r--kernel/locking/rtmutex.c35
-rw-r--r--kernel/locking/rtmutex_common.h12
4 files changed, 19 insertions, 33 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 2ccbbbfcb7b8..6f1b0af00bda 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1462,8 +1462,7 @@ static void rt_mutex_init_task(struct task_struct *p)
{
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 --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
index ac35e648b0e5..f4a74e78d467 100644
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -58,7 +58,7 @@ static void printk_lock(struct rt_mutex *lock, int print_owner)
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 --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 649dc9d3951a..6f3dba6e4e9e 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -271,10 +271,10 @@ rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
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, struct rt_mutex_waiter *waiter)
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, struct rt_mutex_waiter *waiter)
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 *task, struct rt_mutex_waiter *waiter)
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 *task, struct rt_mutex_waiter *waiter)
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 *lock, const char *name,
{
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 --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 8d039b928d61..7453be0485a5 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/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 *lock)
{
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 *lock)
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