Commit cbbce822 authored by NeilBrown's avatar NeilBrown Committed by Trond Myklebust
Browse files

SCHED: add some "wait..on_bit...timeout()" interfaces. 



In commit c1221321
   sched: Allow wait_on_bit_action() functions to support a timeout

I suggested that a "wait_on_bit_timeout()" interface would not meet my
need.  This isn't true - I was just over-engineering.

Including a 'private' field in wait_bit_key instead of a focused
"timeout" field was just premature generalization.  If some other
use is ever found, it can be generalized or added later.

So this patch renames "private" to "timeout" with a meaning "stop
waiting when "jiffies" reaches or passes "timeout",
and adds two of the many possible wait..bit..timeout() interfaces:

wait_on_page_bit_killable_timeout(), which is the one I want to use,
and out_of_line_wait_on_bit_timeout() which is a reasonably general
example.  Others can be added as needed.

Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@primarydata.com>
parent e87b4c7a

include/linux/pagemap.h

+2 −0
Original line number Diff line number Diff line
@@ -502,6 +502,8 @@ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, 
extern void wait_on_page_bit(struct page *page, int bit_nr);



extern int wait_on_page_bit_killable(struct page *page, int bit_nr);

extern int wait_on_page_bit_killable_timeout(struct page *page,

					     int bit_nr, unsigned long timeout);



static inline int wait_on_page_locked_killable(struct page *page)

{

include/linux/wait.h

+4 −1
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ struct wait_bit_key { 
	void			*flags;

	int			bit_nr;

#define WAIT_ATOMIC_T_BIT_NR	-1

	unsigned long		private;

	unsigned long		timeout;

};



struct wait_bit_queue {
@@ -154,6 +154,7 @@ int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_ac 
void wake_up_bit(void *, int);

void wake_up_atomic_t(atomic_t *);

int out_of_line_wait_on_bit(void *, int, wait_bit_action_f *, unsigned);

int out_of_line_wait_on_bit_timeout(void *, int, wait_bit_action_f *, unsigned, unsigned long);

int out_of_line_wait_on_bit_lock(void *, int, wait_bit_action_f *, unsigned);

int out_of_line_wait_on_atomic_t(atomic_t *, int (*)(atomic_t *), unsigned);

wait_queue_head_t *bit_waitqueue(void *, int);
@@ -859,6 +860,8 @@ int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key); 


extern int bit_wait(struct wait_bit_key *);

extern int bit_wait_io(struct wait_bit_key *);

extern int bit_wait_timeout(struct wait_bit_key *);

extern int bit_wait_io_timeout(struct wait_bit_key *);



/**

 * wait_on_bit - wait for a bit to be cleared

kernel/sched/wait.c

+36 −0
Original line number Diff line number Diff line
@@ -343,6 +343,18 @@ int __sched out_of_line_wait_on_bit(void *word, int bit, 
}

EXPORT_SYMBOL(out_of_line_wait_on_bit);



int __sched out_of_line_wait_on_bit_timeout(

	void *word, int bit, wait_bit_action_f *action,

	unsigned mode, unsigned long timeout)

{

	wait_queue_head_t *wq = bit_waitqueue(word, bit);

	DEFINE_WAIT_BIT(wait, word, bit);



	wait.key.timeout = jiffies + timeout;

	return __wait_on_bit(wq, &wait, action, mode);

}

EXPORT_SYMBOL_GPL(out_of_line_wait_on_bit_timeout);



int __sched

__wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q,

			wait_bit_action_f *action, unsigned mode)
@@ -520,3 +532,27 @@ __sched int bit_wait_io(struct wait_bit_key *word) 
	return 0;

}

EXPORT_SYMBOL(bit_wait_io);



__sched int bit_wait_timeout(struct wait_bit_key *word)

{

	unsigned long now = ACCESS_ONCE(jiffies);

	if (signal_pending_state(current->state, current))

		return 1;

	if (time_after_eq(now, word->timeout))

		return -EAGAIN;

	schedule_timeout(word->timeout - now);

	return 0;

}

EXPORT_SYMBOL_GPL(bit_wait_timeout);



__sched int bit_wait_io_timeout(struct wait_bit_key *word)

{

	unsigned long now = ACCESS_ONCE(jiffies);

	if (signal_pending_state(current->state, current))

		return 1;

	if (time_after_eq(now, word->timeout))

		return -EAGAIN;

	io_schedule_timeout(word->timeout - now);

	return 0;

}

EXPORT_SYMBOL_GPL(bit_wait_io_timeout);

mm/filemap.c

+13 −0
Original line number Diff line number Diff line
@@ -703,6 +703,19 @@ int wait_on_page_bit_killable(struct page *page, int bit_nr) 
			     bit_wait_io, TASK_KILLABLE);

}



int wait_on_page_bit_killable_timeout(struct page *page,

				       int bit_nr, unsigned long timeout)

{

	DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);



	wait.key.timeout = jiffies + timeout;

	if (!test_bit(bit_nr, &page->flags))

		return 0;

	return __wait_on_bit(page_waitqueue(page), &wait,

			     bit_wait_io_timeout, TASK_KILLABLE);

}

EXPORT_SYMBOL_GPL(wait_on_page_bit_killable_timeout);



/**

 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue

 * @page: Page defining the wait queue of interest

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