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author | NeilBrown <neilb@suse.com> | 2018-02-13 08:22:36 +1100 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-16 15:19:09 +0100 |
commit | 0957a2c1d97586893d5ba7ce864b1d7e0b82b162 (patch) | |
tree | 63ef39fa23accf3f81714bb162bb8cf5894c43e9 /include/linux/wait.h | |
parent | 8016ab9ebbda3dee637ac66b9e0f7a74ef6fe9e6 (diff) | |
download | linux-stable-0957a2c1d97586893d5ba7ce864b1d7e0b82b162.tar.gz linux-stable-0957a2c1d97586893d5ba7ce864b1d7e0b82b162.tar.bz2 linux-stable-0957a2c1d97586893d5ba7ce864b1d7e0b82b162.zip |
sched/wait: add wait_event_idle() functions.
The new TASK_IDLE state (TASK_UNINTERRUPTIBLE | __TASK_NOLOAD)
is not much used. One way to make it easier to use is to
add wait_event*() family functions that make use of it.
This patch adds:
wait_event_idle()
wait_event_idle_timeout()
wait_event_idle_exclusive()
wait_event_idle_exclusive_timeout()
This set was chosen because lustre needs them before
it can discard its own l_wait_event() macro.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: Patrick Farrell <paf@cray.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/wait.h')
-rw-r--r-- | include/linux/wait.h | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/include/linux/wait.h b/include/linux/wait.h index 55a611486bac..d9f131ecf708 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -599,6 +599,120 @@ do { \ __ret; \ }) +/** + * wait_event_idle - wait for a condition without contributing to system load + * @wq_head: the waitqueue to wait on + * @condition: a C expression for the event to wait for + * + * The process is put to sleep (TASK_IDLE) until the + * @condition evaluates to true. + * The @condition is checked each time the waitqueue @wq_head is woken up. + * + * wake_up() has to be called after changing any variable that could + * change the result of the wait condition. + * + */ +#define wait_event_idle(wq_head, condition) \ +do { \ + might_sleep(); \ + if (!(condition)) \ + ___wait_event(wq_head, condition, TASK_IDLE, 0, 0, schedule()); \ +} while (0) + +/** + * wait_event_idle_exclusive - wait for a condition with contributing to system load + * @wq_head: the waitqueue to wait on + * @condition: a C expression for the event to wait for + * + * The process is put to sleep (TASK_IDLE) until the + * @condition evaluates to true. + * The @condition is checked each time the waitqueue @wq_head is woken up. + * + * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag + * set thus if other processes wait on the same list, when this + * process is woken further processes are not considered. + * + * wake_up() has to be called after changing any variable that could + * change the result of the wait condition. + * + */ +#define wait_event_idle_exclusive(wq_head, condition) \ +do { \ + might_sleep(); \ + if (!(condition)) \ + ___wait_event(wq_head, condition, TASK_IDLE, 1, 0, schedule()); \ +} while (0) + +#define __wait_event_idle_timeout(wq_head, condition, timeout) \ + ___wait_event(wq_head, ___wait_cond_timeout(condition), \ + TASK_IDLE, 0, timeout, \ + __ret = schedule_timeout(__ret)) + +/** + * wait_event_idle_timeout - sleep without load until a condition becomes true or a timeout elapses + * @wq_head: the waitqueue to wait on + * @condition: a C expression for the event to wait for + * @timeout: timeout, in jiffies + * + * The process is put to sleep (TASK_IDLE) until the + * @condition evaluates to true. The @condition is checked each time + * the waitqueue @wq_head is woken up. + * + * wake_up() has to be called after changing any variable that could + * change the result of the wait condition. + * + * 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_idle_timeout(wq_head, condition, timeout) \ +({ \ + long __ret = timeout; \ + might_sleep(); \ + if (!___wait_cond_timeout(condition)) \ + __ret = __wait_event_idle_timeout(wq_head, condition, timeout); \ + __ret; \ +}) + +#define __wait_event_idle_exclusive_timeout(wq_head, condition, timeout) \ + ___wait_event(wq_head, ___wait_cond_timeout(condition), \ + TASK_IDLE, 1, timeout, \ + __ret = schedule_timeout(__ret)) + +/** + * wait_event_idle_exclusive_timeout - sleep without load until a condition becomes true or a timeout elapses + * @wq_head: the waitqueue to wait on + * @condition: a C expression for the event to wait for + * @timeout: timeout, in jiffies + * + * The process is put to sleep (TASK_IDLE) until the + * @condition evaluates to true. The @condition is checked each time + * the waitqueue @wq_head is woken up. + * + * The process is put on the wait queue with an WQ_FLAG_EXCLUSIVE flag + * set thus if other processes wait on the same list, when this + * process is woken further processes are not considered. + * + * wake_up() has to be called after changing any variable that could + * change the result of the wait condition. + * + * 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_idle_exclusive_timeout(wq_head, condition, timeout) \ +({ \ + long __ret = timeout; \ + might_sleep(); \ + if (!___wait_cond_timeout(condition)) \ + __ret = __wait_event_idle_exclusive_timeout(wq_head, condition, timeout);\ + __ret; \ +}) + extern int do_wait_intr(wait_queue_head_t *, wait_queue_entry_t *); extern int do_wait_intr_irq(wait_queue_head_t *, wait_queue_entry_t *); |