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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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5
include/linux/init_task.h
View File

@ -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

11
include/linux/rtmutex.h
View File

@ -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)}

3
include/linux/sched.h
View File

@ -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: */

3
kernel/fork.c
View File

@ -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

2
kernel/locking/rtmutex-debug.c
View File

@ -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);
}

35
kernel/locking/rtmutex.c
View File

@ -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);

12
kernel/locking/rtmutex_common.h
View File

@ -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