sched/wait: fix and then kill abort_exclusive_wait()
v2 cover sched/wait: fix and then kill abort_exclusive_wait()
Quoted 10 lines · Peter Zijlstra
Quoted 2 lines · Oleg Nesterov
And, if you agree with this change I will try to change
__wait_event()as well and killabort_exclusive_wait().Yeah, I think this'll work. Please send a new series with 'enhanced' changelog so that when we have to look at this again in a few weeks/months time we won't be cursing at ourselves for how the heck it was supposed to work.
OK, thanks, please see V2.
I think it makes sense to change ___wait_event() first, this simplifies the documentation in __wait_on_bit_lock().
See also 4/4, it is new and simple. From the changelog
In particular we are ready to remove the signal_pending_state() checks from wait_bit_action_f helpers and change __wait_on_bit_lock() to use prepare_to_wait_event().
Yes. The necessary change is trivial. But this probably needs a separate discussion/testing because we need to re-investigate the problem which was somehow fixed by 68985633bccb60 "sched/wait: Fix signal handling in bit wait helpers".
Oleg.
include/linux/wait.h | 17 ++------- kernel/sched/wait.c | 101 ++++++++++++++++++++++++--------------------------- 2 files changed, 52 insertions(+), 66 deletions(-)
PATCH v2 1/4 sched/wait: abort_exclusive_wait() should pass TASK_NORMAL to wake_up()
Otherwise this logic only works if mode is "compatible" with another exclusive waiter.
If some wq has both TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE waiters, abort_exclusive_wait() won't wait an uninterruptible waiter.
The main user is __wait_on_bit_lock() and currently it is fine but only because TASK_KILLABLE includes TASK_UNINTERRUPTIBLE and we do not have lock_page_interruptible() yet.
Just use TASK_NORMAL and remove the "mode" arg from abort_exclusive_wait(). Yes, this means that (say) wake_up_interruptible() can wake up the non- interruptible waiter(s), but I think this is fine. And in fact I think that abort_exclusive_wait() must die, see the next change.
--- include/linux/wait.h | 6 +++--- kernel/sched/wait.c | 8 +++----- 2 files changed, 6 insertions(+), 8 deletions(-)
include/linux/wait.h +3 -3
@@ -281,8 +281,8 @@ wait_queue_head_t *bit_waitqueue(void *, int);if (___wait_is_interruptible (state) && __int) { \ __ret = __int; \if (exclusive) { \ -abort_exclusive_wait (&wq, &__wait, \ - state,NULL ); \ +abort_exclusive_wait (&wq, &__wait, \ +NULL ); \ goto __out; \ } \break ; \
@@ -976,7 +976,7 @@ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);void prepare_to_wait_exclusive (wait_queue_head_t *q,wait_queue_t *wait,int state);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state);void finish_wait (wait_queue_head_t *q,wait_queue_t *wait); -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,unsigned int mode,void *key); +void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key);long wait_woken (wait_queue_t *wait,unsigned mode,long timeout);int woken_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);int autoremove_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);
kernel/sched/wait.c +3 -5
@@ -259,7 +259,6 @@ EXPORT_SYMBOL(finish_wait);* abort_exclusive_wait - abort exclusive waiting in a queue * @q: waitqueue waited on * @wait: wait descriptor -* @mode: runstate of the waiter to be woken * @key: key to identify a wait bit queue or %NULL * * Sets current thread back to running state and removes
@@ -273,8 +272,7 @@ EXPORT_SYMBOL(finish_wait);* aborts and is woken up concurrently and no one wakes up * the next waiter. */ -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait, -unsigned int mode,void *key) +void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key) {unsigned long flags;
@@ -283,7 +281,7 @@ void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,if (!list_empty (&wait->task_list))list_del_init (&wait->task_list);else if (waitqueue_active (q)) -__wake_up_locked_key (q, mode, key); +__wake_up_locked_key (q,TASK_NORMAL , key);spin_unlock_irqrestore (&q->lock, flags); }EXPORT_SYMBOL (abort_exclusive_wait);
@@ -434,7 +432,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q, ret =action (&q->key, mode);if (!ret)continue ; -abort_exclusive_wait (wq, &q->wait, mode, &q->key); +abort_exclusive_wait (wq, &q->wait, &q->key);return ret; }while (test_and_set_bit (q->key.bit_nr, q->key.flags));finish_wait (wq, &q->wait);
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:sched/core] sched/wait: Fix abort_exclusive_wait(), it should pass TASK_NORMAL to wake_up()
sched/wait: Fix abort_exclusive_wait(), it should pass TASK_NORMAL to wake_up()
Commit-ID: 38a3e1fc1dac480f3672ab22fc97e1f995c80ed7 Gitweb: http://git.kernel.org/tip/38a3e1fc1dac480f3672ab22fc97e1f995c80ed7 Author: Oleg Nesterov <[email protected]> AuthorDate: Tue, 6 Sep 2016 16:00:47 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 30 Sep 2016 10:53:19 +0200
sched/wait: Fix abort_exclusive_wait(), it should pass TASK_NORMAL to wake_up()
Otherwise this logic only works if mode is "compatible" with another exclusive waiter.
If some wq has both TASK_INTERRUPTIBLE and TASK_UNINTERRUPTIBLE waiters, abort_exclusive_wait() won't wait an uninterruptible waiter.
The main user is __wait_on_bit_lock() and currently it is fine but only because TASK_KILLABLE includes TASK_UNINTERRUPTIBLE and we do not have lock_page_interruptible() yet.
Just use TASK_NORMAL and remove the "mode" arg from abort_exclusive_wait(). Yes, this means that (say) wake_up_interruptible() can wake up the non- interruptible waiter(s), but I think this is fine. And in fact I think that abort_exclusive_wait() must die, see the next change.
--- include/linux/wait.h | 6 +++--- kernel/sched/wait.c | 8 +++----- 2 files changed, 6 insertions(+), 8 deletions(-)
include/linux/wait.h +3 -3
@@ -281,8 +281,8 @@ wait_queue_head_t *bit_waitqueue(void *, int);if (___wait_is_interruptible (state) && __int) { \ __ret = __int; \if (exclusive) { \ -abort_exclusive_wait (&wq, &__wait, \ - state,NULL ); \ +abort_exclusive_wait (&wq, &__wait, \ +NULL ); \ goto __out; \ } \break ; \
@@ -989,7 +989,7 @@ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);void prepare_to_wait_exclusive (wait_queue_head_t *q,wait_queue_t *wait,int state);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state);void finish_wait (wait_queue_head_t *q,wait_queue_t *wait); -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,unsigned int mode,void *key); +void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key);long wait_woken (wait_queue_t *wait,unsigned mode,long timeout);int woken_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);int autoremove_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);
kernel/sched/wait.c +3 -5
@@ -259,7 +259,6 @@ EXPORT_SYMBOL(finish_wait);* abort_exclusive_wait - abort exclusive waiting in a queue * @q: waitqueue waited on * @wait: wait descriptor -* @mode: runstate of the waiter to be woken * @key: key to identify a wait bit queue or %NULL * * Sets current thread back to running state and removes
@@ -273,8 +272,7 @@ EXPORT_SYMBOL(finish_wait);* aborts and is woken up concurrently and no one wakes up * the next waiter. */ -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait, -unsigned int mode,void *key) +void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key) {unsigned long flags;
@@ -283,7 +281,7 @@ void abort_exclusive_wait(wait_queue_head_t *q, wait_queue_t *wait,if (!list_empty (&wait->task_list))list_del_init (&wait->task_list);else if (waitqueue_active (q)) -__wake_up_locked_key (q, mode, key); +__wake_up_locked_key (q,TASK_NORMAL , key);spin_unlock_irqrestore (&q->lock, flags); }EXPORT_SYMBOL (abort_exclusive_wait);
@@ -434,7 +432,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q, ret =action (&q->key, mode);if (!ret)continue ; -abort_exclusive_wait (wq, &q->wait, mode, &q->key); +abort_exclusive_wait (wq, &q->wait, &q->key);return ret; }while (test_and_set_bit (q->key.bit_nr, q->key.flags));finish_wait (wq, &q->wait);
PATCH v2 2/4 sched/wait: avoid abort_exclusive_wait() in ___wait_event()
In reply to Oleg Nesterov___wait_event() doesn't really need abort_exclusive_wait(), we can simply change prepare_to_wait_event() to remove the waiter from q->task_list if it was interrupted.
This simplifies the code/logic, and this way prepare_to_wait_event() can have more users, see the next change.
--- include/linux/wait.h | 7 +------ kernel/sched/wait.c | 23 ++++++++++++++++++----- 2 files changed, 19 insertions(+), 11 deletions(-)
include/linux/wait.h +1 -6
@@ -280,12 +280,7 @@ wait_queue_head_t *bit_waitqueue(void *, int); \if (___wait_is_interruptible (state) && __int) { \ __ret = __int; \ -if (exclusive) { \ -abort_exclusive_wait (&wq, &__wait, \ -NULL ); \ - goto __out; \ - } \ -break ; \ + goto __out; \ } \ \ cmd; \
kernel/sched/wait.c +18 -5
@@ -199,15 +199,28 @@ EXPORT_SYMBOL(prepare_to_wait_exclusive);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state) {unsigned long flags; - -if (signal_pending_state (state, current)) -return -ERESTARTSYS ; +long ret =0 ; wait->private = current; wait->func = autoremove_wake_function;spin_lock_irqsave (&q->lock, flags); -if (list_empty (&wait->task_list)) { +if (unlikely (signal_pending_state (state, current))) { +/* +* Exclusive waiter must not fail if it was selected by wakeup, +* it should "consume" the condition we were waiting for. +* +* The caller will recheck the condition and return success if +* we were already woken up, we can not miss the event because +* wakeup locks/unlocks the same q->lock. +* +* But we need to ensure that set-condition + wakeup after that +* can't see us, it should wake up another exclusive waiter if +* we fail. +*/ +list_del_init (&wait->task_list); + ret = -ERESTARTSYS ; + }else if (list_empty (&wait->task_list)) {if (wait->flags &WQ_FLAG_EXCLUSIVE )__add_wait_queue_tail (q, wait);else
@@ -216,7 +229,7 @@ long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state)set_current_state (state);spin_unlock_irqrestore (&q->lock, flags); -return 0 ; +return ret; }EXPORT_SYMBOL (prepare_to_wait_event);
Signature · 1 line
2.5.0
PATCH v3 2/4 sched/wait: avoid abort_exclusive_wait() in ___wait_event()
Quoted 6 lines · Oleg Nesterov
(quoted diff) +5
-0+ if (unlikely(signal_pending_state(state, current))) { + /* + * Exclusive waiter must not fail if it was selected by wakeup, + * it should "consume" the condition we were waiting for. + *
Review
Quoted 10 lines
(quoted diff) +10
-0+ * The caller will recheck the condition and return success if + * we were already woken up, we can not miss the event because + * wakeup locks/unlocks the same q->lock. + * + * But we need to ensure that set-condition + wakeup after that + * can't see us, it should wake up another exclusive waiter if + * we fail. + */ + list_del_init(&wait->task_list); + ret = -ERESTARTSYS;
Yes, but we should not do set_current_state() in this case, please sere V3.
-------------------------------------------------------------------------------
Subject: [PATCH V3 2/4] sched/wait: avoid abort_exclusive_wait() in ___wait_event()
___wait_event() doesn't really need abort_exclusive_wait(), we can simply change prepare_to_wait_event() to remove the waiter from q->task_list if it was interrupted.
This simplifies the code/logic, and this way prepare_to_wait_event() can have more users, see the next change.
--- include/linux/wait.h | 7 +------ kernel/sched/wait.c | 35 +++++++++++++++++++++++++---------- 2 files changed, 26 insertions(+), 16 deletions(-)
include/linux/wait.h +1 -6
@@ -280,12 +280,7 @@ wait_queue_head_t *bit_waitqueue(void *, int); \if (___wait_is_interruptible (state) && __int) { \ __ret = __int; \ -if (exclusive) { \ -abort_exclusive_wait (&wq, &__wait, \ -NULL ); \ - goto __out; \ - } \ -break ; \ + goto __out; \ } \ \ cmd; \
kernel/sched/wait.c +25 -10
@@ -199,24 +199,39 @@ EXPORT_SYMBOL(prepare_to_wait_exclusive);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state) {unsigned long flags; - -if (signal_pending_state (state, current)) -return -ERESTARTSYS ; +long ret =0 ; wait->private = current; wait->func = autoremove_wake_function;spin_lock_irqsave (&q->lock, flags); -if (list_empty (&wait->task_list)) { -if (wait->flags &WQ_FLAG_EXCLUSIVE ) -__add_wait_queue_tail (q, wait); -else -__add_wait_queue (q, wait); +if (unlikely (signal_pending_state (state, current))) { +/* +* Exclusive waiter must not fail if it was selected by wakeup, +* it should "consume" the condition we were waiting for. +* +* The caller will recheck the condition and return success if +* we were already woken up, we can not miss the event because +* wakeup locks/unlocks the same q->lock. +* +* But we need to ensure that set-condition + wakeup after that +* can't see us, it should wake up another exclusive waiter if +* we fail. +*/ +list_del_init (&wait->task_list); + ret = -ERESTARTSYS ; + }else { +if (list_empty (&wait->task_list)) { +if (wait->flags &WQ_FLAG_EXCLUSIVE ) +__add_wait_queue_tail (q, wait); +else +__add_wait_queue (q, wait); + } +set_current_state (state); } -set_current_state (state);spin_unlock_irqrestore (&q->lock, flags); -return 0 ; +return ret; }EXPORT_SYMBOL (prepare_to_wait_event);
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:sched/core] sched/wait: Avoid abort_exclusive_wait() in ___wait_event()
sched/wait: Avoid abort_exclusive_wait() in ___wait_event()
Commit-ID: b1ea06a90f528e516929a4da1d9b8838752bceb9 Gitweb: http://git.kernel.org/tip/b1ea06a90f528e516929a4da1d9b8838752bceb9 Author: Oleg Nesterov <[email protected]> AuthorDate: Thu, 8 Sep 2016 18:48:15 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 30 Sep 2016 10:53:44 +0200
sched/wait: Avoid abort_exclusive_wait() in ___wait_event()
___wait_event() doesn't really need abort_exclusive_wait(), we can simply change prepare_to_wait_event() to remove the waiter from q->task_list if it was interrupted.
This simplifies the code/logic, and this way prepare_to_wait_event() can have more users, see the next change.
--
include/linux/wait.h | 7 +------ kernel/sched/wait.c | 35 +++++++++++++++++++++++++---------- 2 files changed, 26 insertions(+), 16 deletions(-) --- include/linux/wait.h | 7 +------ kernel/sched/wait.c | 35 +++++++++++++++++++++++++---------- 2 files changed, 26 insertions(+), 16 deletions(-)
include/linux/wait.h +1 -6
@@ -280,12 +280,7 @@ wait_queue_head_t *bit_waitqueue(void *, int); \if (___wait_is_interruptible (state) && __int) { \ __ret = __int; \ -if (exclusive) { \ -abort_exclusive_wait (&wq, &__wait, \ -NULL ); \ - goto __out; \ - } \ -break ; \ + goto __out; \ } \ \ cmd; \
kernel/sched/wait.c +25 -10
@@ -199,24 +199,39 @@ EXPORT_SYMBOL(prepare_to_wait_exclusive);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state) {unsigned long flags; - -if (signal_pending_state (state, current)) -return -ERESTARTSYS ; +long ret =0 ; wait->private = current; wait->func = autoremove_wake_function;spin_lock_irqsave (&q->lock, flags); -if (list_empty (&wait->task_list)) { -if (wait->flags &WQ_FLAG_EXCLUSIVE ) -__add_wait_queue_tail (q, wait); -else -__add_wait_queue (q, wait); +if (unlikely (signal_pending_state (state, current))) { +/* +* Exclusive waiter must not fail if it was selected by wakeup, +* it should "consume" the condition we were waiting for. +* +* The caller will recheck the condition and return success if +* we were already woken up, we can not miss the event because +* wakeup locks/unlocks the same q->lock. +* +* But we need to ensure that set-condition + wakeup after that +* can't see us, it should wake up another exclusive waiter if +* we fail. +*/ +list_del_init (&wait->task_list); + ret = -ERESTARTSYS ; + }else { +if (list_empty (&wait->task_list)) { +if (wait->flags &WQ_FLAG_EXCLUSIVE ) +__add_wait_queue_tail (q, wait); +else +__add_wait_queue (q, wait); + } +set_current_state (state); } -set_current_state (state);spin_unlock_irqrestore (&q->lock, flags); -return 0 ; +return ret; }EXPORT_SYMBOL (prepare_to_wait_event);
PATCH v2 3/4 sched/wait: avoid abort_exclusive_wait() in __wait_on_bit_lock()
In reply to Oleg Nesterov__wait_on_bit_lock() doesn't need abort_exclusive_wait() too. Right now it can't use prepare_to_wait_event() (see the next change), but it can do the additional finish_wait() if action() fails.
abort_exclusive_wait() no longer has callers, remove it.
--- include/linux/wait.h | 1 - kernel/sched/wait.c | 64 +++++++++++++++++----------------------------------- 2 files changed, 21 insertions(+), 44 deletions(-)
include/linux/wait.h +0 -1
@@ -971,7 +971,6 @@ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);void prepare_to_wait_exclusive (wait_queue_head_t *q,wait_queue_t *wait,int state);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state);void finish_wait (wait_queue_head_t *q,wait_queue_t *wait); -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key);long wait_woken (wait_queue_t *wait,unsigned mode,long timeout);int woken_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);int autoremove_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);
kernel/sched/wait.c +21 -43
78 lines not on this page · raw message
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:sched/core] sched/wait: Avoid abort_exclusive_wait() in __wait_on_bit_lock()
sched/wait: Avoid abort_exclusive_wait() in __wait_on_bit_lock()
Commit-ID: eaf9ef52241b545fe63621266bfc6fd8b06559ff Gitweb: http://git.kernel.org/tip/eaf9ef52241b545fe63621266bfc6fd8b06559ff Author: Oleg Nesterov <[email protected]> AuthorDate: Tue, 6 Sep 2016 16:00:53 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 30 Sep 2016 10:54:03 +0200
sched/wait: Avoid abort_exclusive_wait() in __wait_on_bit_lock()
__wait_on_bit_lock() doesn't need abort_exclusive_wait() too. Right now it can't use prepare_to_wait_event() (see the next change), but it can do the additional finish_wait() if action() fails.
abort_exclusive_wait() no longer has callers, remove it.
--- include/linux/wait.h | 1 - kernel/sched/wait.c | 64 +++++++++++++++++----------------------------------- 2 files changed, 21 insertions(+), 44 deletions(-)
include/linux/wait.h +0 -1
@@ -984,7 +984,6 @@ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state);void prepare_to_wait_exclusive (wait_queue_head_t *q,wait_queue_t *wait,int state);long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state);void finish_wait (wait_queue_head_t *q,wait_queue_t *wait); -void abort_exclusive_wait (wait_queue_head_t *q,wait_queue_t *wait,void *key);long wait_woken (wait_queue_t *wait,unsigned mode,long timeout);int woken_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);int autoremove_wake_function (wait_queue_t *wait,unsigned mode,int sync,void *key);
kernel/sched/wait.c +21 -43
78 lines not on this page · raw message
PATCH v2 4/4 sched/wait: introduce init_wait_entry()
In reply to Oleg NesterovThe partial initialization of wait_queue_t in prepare_to_wait_event() looks ugly. This was done to shrink .text, but we can simply add the new helper which does the full initialization and shrink the compiled code a bit more.
And. This way prepare_to_wait_event() can have more users. In particular we are ready to remove the signal_pending_state() checks from wait_bit_action_f helpers and change __wait_on_bit_lock() to use prepare_to_wait_event().
--- include/linux/wait.h | 9 +++------ kernel/sched/wait.c | 12 +++++++++--- 2 files changed, 12 insertions(+), 9 deletions(-)
include/linux/wait.h +3 -6
@@ -248,6 +248,8 @@ wait_queue_head_t *bit_waitqueue(void *, int); (!__builtin_constant_p (state) || \ state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \ +extern void init_wait_entry (wait_queue_t *__wait,int flags); +/* * The below macro ___wait_event() has an explicit shadow of the __ret * variable when used from the wait_event_*() macros.
@@ -266,12 +268,7 @@ wait_queue_head_t *bit_waitqueue(void *, int);wait_queue_t __wait; \long __ret = ret;/* explicit shadow */ \ \ -INIT_LIST_HEAD (&__wait.task_list); \ -if (exclusive) \ - __wait.flags =WQ_FLAG_EXCLUSIVE ; \ -else \ - __wait.flags =0 ; \ - \ +init_wait_entry (&__wait, exclusive ?WQ_FLAG_EXCLUSIVE :0 ); \for (;;) { \long __int =prepare_to_wait_event (&wq, &__wait, state);\ \
kernel/sched/wait.c +9 -3
@@ -196,14 +196,20 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) }EXPORT_SYMBOL (prepare_to_wait_exclusive); +void init_wait_entry (wait_queue_t *wait,int flags) +{ + wait->flags = flags; + wait->private = current; + wait->func = autoremove_wake_function; +INIT_LIST_HEAD (&wait->task_list); +} +EXPORT_SYMBOL (init_wait_entry); +long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state) {unsigned long flags;long ret =0 ; - wait->private = current; - wait->func = autoremove_wake_function; -spin_lock_irqsave (&q->lock, flags);if (unlikely (signal_pending_state (state, current))) {/*
Signature · 1 line
2.5.0
tip-bot for Oleg Nesterov
merge bot[tip:sched/core] sched/wait: Introduce init_wait_entry()
sched/wait: Introduce init_wait_entry()
Commit-ID: 0176beaffbe9ed627b6a4dfa61d640f1a848086f Gitweb: http://git.kernel.org/tip/0176beaffbe9ed627b6a4dfa61d640f1a848086f Author: Oleg Nesterov <[email protected]> AuthorDate: Tue, 6 Sep 2016 16:00:55 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Fri, 30 Sep 2016 10:54:03 +0200
sched/wait: Introduce init_wait_entry()
The partial initialization of wait_queue_t in prepare_to_wait_event() looks ugly. This was done to shrink .text, but we can simply add the new helper which does the full initialization and shrink the compiled code a bit more.
And. This way prepare_to_wait_event() can have more users. In particular we are ready to remove the signal_pending_state() checks from wait_bit_action_f helpers and change __wait_on_bit_lock() to use prepare_to_wait_event().
--- include/linux/wait.h | 9 +++------ kernel/sched/wait.c | 12 +++++++++--- 2 files changed, 12 insertions(+), 9 deletions(-)
include/linux/wait.h +3 -6
@@ -248,6 +248,8 @@ wait_queue_head_t *bit_waitqueue(void *, int); (!__builtin_constant_p (state) || \ state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \ +extern void init_wait_entry (wait_queue_t *__wait,int flags); +/* * The below macro ___wait_event() has an explicit shadow of the __ret * variable when used from the wait_event_*() macros.
@@ -266,12 +268,7 @@ wait_queue_head_t *bit_waitqueue(void *, int);wait_queue_t __wait; \long __ret = ret;/* explicit shadow */ \ \ -INIT_LIST_HEAD (&__wait.task_list); \ -if (exclusive) \ - __wait.flags =WQ_FLAG_EXCLUSIVE ; \ -else \ - __wait.flags =0 ; \ - \ +init_wait_entry (&__wait, exclusive ?WQ_FLAG_EXCLUSIVE :0 ); \for (;;) { \long __int =prepare_to_wait_event (&wq, &__wait, state);\ \
kernel/sched/wait.c +9 -3
@@ -196,14 +196,20 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) }EXPORT_SYMBOL (prepare_to_wait_exclusive); +void init_wait_entry (wait_queue_t *wait,int flags) +{ + wait->flags = flags; + wait->private = current; + wait->func = autoremove_wake_function; +INIT_LIST_HEAD (&wait->task_list); +} +EXPORT_SYMBOL (init_wait_entry); +long prepare_to_wait_event (wait_queue_head_t *q,wait_queue_t *wait,int state) {unsigned long flags;long ret =0 ; - wait->private = current; - wait->func = autoremove_wake_function; -spin_lock_irqsave (&q->lock, flags);if (unlikely (signal_pending_state (state, current))) {/*