Messages in this thread Patch in this message | | | From | NeilBrown <> | Date | Fri, 22 Dec 2017 14:11:04 +1100 | Subject | [PATCH 1/2] sched/wait: add wait_event_idle() functions. |
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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()
This set were chosen because lustre needs them before it can discard its own l_wait_event() macro.
Signed-off-by: NeilBrown <neilb@suse.com> --- include/linux/wait.h | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 77 insertions(+)
diff --git a/include/linux/wait.h b/include/linux/wait.h index 158715445ffb..3aea0780c9d0 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -597,6 +597,83 @@ do { \ __ret; \ }) +/** + * wait_event_idle - 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. + * + * 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 when other process waits process on the list if this + * process is awaken 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 gets 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_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 *);
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