From 6b44f519017b219a12b37173c7eef8dfce2c0100 Mon Sep 17 00:00:00 2001 From: Scot Doyle Date: Sun, 24 Aug 2014 17:12:27 +0000 Subject: sched/wait: Document timeout corner case The timeout may elapse without 0 being returned, such as when waiting on an unused queue. Document this possibility. Signed-off-by: Scot Doyle Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Link: http://lkml.kernel.org/r/alpine.LNX.2.11.1408241710070.6462@localhost.localdomain Signed-off-by: Ingo Molnar --- include/linux/wait.h | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) (limited to 'include/linux/wait.h') diff --git a/include/linux/wait.h b/include/linux/wait.h index 6fb1ba5f9b2f..034f6fc7c65f 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -280,9 +280,11 @@ do { \ * wake_up() has to be called after changing any variable that could * change the result of the wait condition. * - * The function returns 0 if the @timeout elapsed, or the remaining - * jiffies (at least 1) if the @condition evaluated to %true before - * the @timeout elapsed. + * Returns: + * 0 if the @condition evaluated to %false after the @timeout elapsed, + * 1 if the @condition evaluated to %true after the @timeout elapsed, + * or the remaining jiffies (at least 1) if the @condition evaluated + * to %true before the @timeout elapsed. */ #define wait_event_timeout(wq, condition, timeout) \ ({ \ @@ -363,9 +365,11 @@ do { \ * change the result of the wait condition. * * Returns: - * 0 if the @timeout elapsed, -%ERESTARTSYS if it was interrupted by - * a signal, or the remaining jiffies (at least 1) if the @condition - * evaluated to %true before the @timeout elapsed. + * 0 if the @condition evaluated to %false after the @timeout elapsed, + * 1 if the @condition evaluated to %true after the @timeout elapsed, + * the remaining jiffies (at least 1) if the @condition evaluated + * to %true before the @timeout elapsed, or -%ERESTARTSYS if it was + * interrupted by a signal. */ #define wait_event_interruptible_timeout(wq, condition, timeout) \ ({ \ -- cgit v1.2.3 From cbbce82209490df8b68da9aec0d642451fe0a668 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Thu, 25 Sep 2014 13:55:19 +1000 Subject: SCHED: add some "wait..on_bit...timeout()" interfaces. In commit c1221321b7c25b53204447cff9949a6d5a7ddddc 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: Peter Zijlstra (Intel) Signed-off-by: NeilBrown Acked-by: Ingo Molnar Signed-off-by: Trond Myklebust --- include/linux/wait.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/linux/wait.h') diff --git a/include/linux/wait.h b/include/linux/wait.h index 6fb1ba5f9b2f..80115bf88671 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -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 -- cgit v1.2.3