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Subject[PATCH 1/2] wait: introduce wait_event_common(wq, condition, state, timeout)
1. wait_event_timeout(wq, true, 0) returns zero, I think this is
wrong and should be fixed.

__wait_event_timeout() was already changed by 4c663cfc but we
need the same logic in wait_event_timeout() if the fast-path
check succeeds.

2. wait_event_timeout/__wait_event_timeout interface do not match
wait_event(), you can't use __wait_event_timeout() instead of
wait_event_timeout() if you do not need the fast-path check.

3. wait_event_* macros duplicate the same code.

This patch adds a single helper wait_event_common() which hopefully
does everything right. Compiler optimizes out the "dead" code when
we do not need signal_pending/schedule_timeout.

With this patch "size vmlinux" reports that .text/data shrinks but
I think this depends on gcc/config.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
---
include/linux/wait.h | 181 +++++++++++++++++++------------------------------
1 files changed, 70 insertions(+), 111 deletions(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 1133695..392c54d 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -173,18 +173,52 @@ wait_queue_head_t *bit_waitqueue(void *, int);
#define wake_up_interruptible_sync_poll(x, m) \
__wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))

-#define __wait_event(wq, condition) \
-do { \
+#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_event_common(wq, condition, state, tout) \
+({ \
DEFINE_WAIT(__wait); \
+ long __ret = 0, __tout = tout; \
\
for (;;) { \
- prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
- if (condition) \
+ prepare_to_wait(&wq, &__wait, state); \
+ if (condition) { \
+ __ret = __wait_no_timeout(tout) ?: __tout ?: 1; \
+ break; \
+ } \
+ \
+ if (__wait_signal_pending(state)) { \
+ __ret = -ERESTARTSYS; \
+ break; \
+ } \
+ \
+ if (__wait_no_timeout(tout)) \
+ schedule(); \
+ else if (__tout) \
+ __tout = schedule_timeout(__tout); \
+ else \
break; \
- schedule(); \
} \
finish_wait(&wq, &__wait); \
-} while (0)
+ __ret; \
+})
+
+#define wait_event_common(wq, condition, state, tout) \
+({ \
+ long __ret; \
+ if (condition) \
+ __ret = __wait_no_timeout(tout) ?: (tout) ?: 1; \
+ else \
+ __ret = __wait_event_common(wq, condition, state, tout);\
+ __ret; \
+})

/**
* wait_event - sleep until a condition gets true
@@ -198,29 +232,13 @@ do { \
* wake_up() has to be called after changing any variable that could
* change the result of the wait condition.
*/
-#define wait_event(wq, condition) \
-do { \
- if (condition) \
- break; \
- __wait_event(wq, condition); \
-} while (0)
+#define __wait_event(wq, condition) \
+ __wait_event_common(wq, condition, \
+ TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT) \

-#define __wait_event_timeout(wq, condition, ret) \
-do { \
- DEFINE_WAIT(__wait); \
- \
- for (;;) { \
- prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
- if (condition) \
- break; \
- ret = schedule_timeout(ret); \
- if (!ret) \
- break; \
- } \
- if (!ret && (condition)) \
- ret = 1; \
- finish_wait(&wq, &__wait); \
-} while (0)
+#define wait_event(wq, condition) \
+ wait_event_common(wq, condition, \
+ TASK_UNINTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT) \

/**
* wait_event_timeout - sleep until a condition gets true or a timeout elapses
@@ -239,31 +257,13 @@ do { \
* jiffies (at least 1) if the @condition evaluated to %true before
* the @timeout elapsed.
*/
-#define wait_event_timeout(wq, condition, timeout) \
-({ \
- long __ret = timeout; \
- if (!(condition)) \
- __wait_event_timeout(wq, condition, __ret); \
- __ret; \
-})
+#define __wait_event_timeout(wq, condition, timeout) \
+ __wait_event_common(wq, condition, \
+ TASK_UNINTERRUPTIBLE, timeout)

-#define __wait_event_interruptible(wq, condition, ret) \
-do { \
- DEFINE_WAIT(__wait); \
- \
- for (;;) { \
- prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
- if (condition) \
- break; \
- if (!signal_pending(current)) { \
- schedule(); \
- continue; \
- } \
- ret = -ERESTARTSYS; \
- break; \
- } \
- finish_wait(&wq, &__wait); \
-} while (0)
+#define wait_event_timeout(wq, condition, timeout) \
+ wait_event_common(wq, condition, \
+ TASK_UNINTERRUPTIBLE, timeout)

/**
* wait_event_interruptible - sleep until a condition gets true
@@ -280,35 +280,13 @@ do { \
* The function will return -ERESTARTSYS if it was interrupted by a
* signal and 0 if @condition evaluated to true.
*/
-#define wait_event_interruptible(wq, condition) \
-({ \
- int __ret = 0; \
- if (!(condition)) \
- __wait_event_interruptible(wq, condition, __ret); \
- __ret; \
-})
+#define __wait_event_interruptible(wq, condition) \
+ __wait_event_common(wq, condition, \
+ TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT)

-#define __wait_event_interruptible_timeout(wq, condition, ret) \
-do { \
- DEFINE_WAIT(__wait); \
- \
- for (;;) { \
- prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
- if (condition) \
- break; \
- if (!signal_pending(current)) { \
- ret = schedule_timeout(ret); \
- if (!ret) \
- break; \
- continue; \
- } \
- ret = -ERESTARTSYS; \
- break; \
- } \
- if (!ret && (condition)) \
- ret = 1; \
- finish_wait(&wq, &__wait); \
-} while (0)
+#define wait_event_interruptible(wq, condition) \
+ wait_event_common(wq, condition, \
+ TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT)

/**
* wait_event_interruptible_timeout - sleep until a condition gets true or a timeout elapses
@@ -328,13 +306,13 @@ do { \
* a signal, or the remaining jiffies (at least 1) if the @condition
* evaluated to %true before the @timeout elapsed.
*/
+#define __wait_event_interruptible_timeout(wq, condition, timeout) \
+ __wait_event_common(wq, condition, \
+ TASK_INTERRUPTIBLE, timeout)
+
#define wait_event_interruptible_timeout(wq, condition, timeout) \
-({ \
- long __ret = timeout; \
- if (!(condition)) \
- __wait_event_interruptible_timeout(wq, condition, __ret); \
- __ret; \
-})
+ wait_event_common(wq, condition, \
+ TASK_INTERRUPTIBLE, timeout)

#define __wait_event_hrtimeout(wq, condition, timeout, state) \
({ \
@@ -601,24 +579,6 @@ do { \



-#define __wait_event_killable(wq, condition, ret) \
-do { \
- DEFINE_WAIT(__wait); \
- \
- for (;;) { \
- prepare_to_wait(&wq, &__wait, TASK_KILLABLE); \
- if (condition) \
- break; \
- if (!fatal_signal_pending(current)) { \
- schedule(); \
- continue; \
- } \
- ret = -ERESTARTSYS; \
- break; \
- } \
- finish_wait(&wq, &__wait); \
-} while (0)
-
/**
* wait_event_killable - sleep until a condition gets true
* @wq: the waitqueue to wait on
@@ -634,14 +594,13 @@ do { \
* The function will return -ERESTARTSYS if it was interrupted by a
* signal and 0 if @condition evaluated to true.
*/
-#define wait_event_killable(wq, condition) \
-({ \
- int __ret = 0; \
- if (!(condition)) \
- __wait_event_killable(wq, condition, __ret); \
- __ret; \
-})
+#define __wait_event_killable(wq, condition) \
+ __wait_event_common(wq, condition, \
+ TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT)

+#define wait_event_killable(wq, condition) \
+ wait_event_common(wq, condition, \
+ TASK_KILLABLE, MAX_SCHEDULE_TIMEOUT)

#define __wait_event_lock_irq(wq, condition, lock, cmd) \
do { \
--
1.5.5.1



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