From: Oleg Nesterov Subject: wait: introduce prepare_to_wait_event() Add the new helper, prepare_to_wait_event() which should only be used by wait_event_common/etc. prepare_to_wait_event() returns -ERESTARTSYS if signal_pending_state() is true, otherwise it calls prepare_to_wait(). This allows to uninline the signal-pending checks in wait_event_*. Also, it can initialize wait->private/func. We do not care they were already initialized, the values are the same. This also shaves a couple of insns from the inlined code. Unlike the previous change, this patch "reliably" shrinks the size of generated code for every wait_event*() call, - 4977769 2930984 10104832 18013585 112dd91 vmlinux + 4976847 2930984 10104832 18012663 112d9f7 vmlinux on my build. Signed-off-by: Oleg Nesterov Reviewed-by: Tejun Heo Cc: Daniel Vetter Cc: Imre Deak Cc: Lukas Czerner Signed-off-by: Andrew Morton --- [ dileks: v2: Refresh to fit on top of my revert-wait.h-next20130628 patchset. ] include/linux/wait.h | 22 +++++++++++----------- kernel/wait.c | 13 +++++++++++++ 2 files changed, 24 insertions(+), 11 deletions(-) diff -puN include/linux/wait.h~wait-introduce-prepare_to_wait_event include/linux/wait.h --- a/include/linux/wait.h~wait-introduce-prepare_to_wait_event +++ a/include/linux/wait.h @@ -182,19 +182,20 @@ wait_queue_head_t *bit_waitqueue(void *, #define __wait_no_timeout(tout) \ (__builtin_constant_p(tout) && (tout) == MAX_SCHEDULE_TIMEOUT) -/* uglified signal_pending_state() optimized for constant state */ -#define __wait_signal_pending(state) \ - ((state == TASK_INTERRUPTIBLE) ? signal_pending(current) : \ - (state == TASK_KILLABLE) ? fatal_signal_pending(current) : \ - 0) +#define __wait_interruptible(state) \ + (!__builtin_constant_p(state) || \ + state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) #define __wait_event_common(wq, condition, state, tout) \ ({ \ - DEFINE_WAIT(__wait); \ - long __ret = 0, __tout = tout; \ + long __ret, __tout = tout; \ + wait_queue_t __wait; \ + \ + INIT_LIST_HEAD(&__wait.task_list); \ + __wait.flags = 0; \ \ for (;;) { \ - prepare_to_wait(&wq, &__wait, state); \ + __ret = prepare_to_wait_event(&wq, &__wait, state); \ if (condition) { \ __ret = __wait_no_timeout(tout); \ if (!__ret) { \ @@ -204,10 +205,8 @@ wait_queue_head_t *bit_waitqueue(void *, break; \ } \ \ - if (__wait_signal_pending(state)) { \ - __ret = -ERESTARTSYS; \ + if (__wait_interruptible(state) && __ret) \ break; \ - } \ \ if (__wait_no_timeout(tout)) \ schedule(); \ @@ -791,6 +790,7 @@ extern long interruptible_sleep_on_timeo * Waitqueues which are removed from the waitqueue_head at wakeup time */ void prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state); +int prepare_to_wait_event(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); 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, diff -puN kernel/wait.c~wait-introduce-prepare_to_wait_event kernel/wait.c --- a/kernel/wait.c~wait-introduce-prepare_to_wait_event +++ a/kernel/wait.c @@ -78,6 +78,19 @@ prepare_to_wait(wait_queue_head_t *q, wa } EXPORT_SYMBOL(prepare_to_wait); +int prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state) +{ + if (signal_pending_state(state, current)) + return -ERESTARTSYS; + + wait->private = current; + wait->func = autoremove_wake_function; + prepare_to_wait(q, wait, state); + + return 0; +} +EXPORT_SYMBOL(prepare_to_wait_event); + void prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state) { _