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locking/rtmutex: replace top-waiter and pi_waiters leftmost caching

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... 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>
This commit is contained in:
Davidlohr Bueso
2017-09-08 16:15:01 -07:00
committed by Linus Torvalds
parent 2161573ecd
commit a23ba907d5
7 changed files with 27 additions and 44 deletions
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35
kernel/locking/rtmutex.c
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@@ -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);