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Subject[PATCH V2 4/4] sched/wait: introduce init_wait_entry()
The partial initialization of wait_queue_t in prepare_to_wait_event() looks
ugly. This was done to shrink .text, but we can simply add the new helper
which does the full initialization and shrink the compiled code a bit more.

And. This way prepare_to_wait_event() can have more users. In particular we
are ready to remove the signal_pending_state() checks from wait_bit_action_f
helpers and change __wait_on_bit_lock() to use prepare_to_wait_event().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
include/linux/wait.h | 9 +++------
kernel/sched/wait.c | 12 +++++++++---
2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 52953a5..1b8a930 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -248,6 +248,8 @@ wait_queue_head_t *bit_waitqueue(void *, int);
(!__builtin_constant_p(state) || \
state == TASK_INTERRUPTIBLE || state == TASK_KILLABLE) \

+extern void init_wait_entry(wait_queue_t *__wait, int flags);
+
/*
* The below macro ___wait_event() has an explicit shadow of the __ret
* variable when used from the wait_event_*() macros.
@@ -266,12 +268,7 @@ wait_queue_head_t *bit_waitqueue(void *, int);
wait_queue_t __wait; \
long __ret = ret; /* explicit shadow */ \
\
- INIT_LIST_HEAD(&__wait.task_list); \
- if (exclusive) \
- __wait.flags = WQ_FLAG_EXCLUSIVE; \
- else \
- __wait.flags = 0; \
- \
+ init_wait_entry(&__wait, exclusive ? WQ_FLAG_EXCLUSIVE : 0); \
for (;;) { \
long __int = prepare_to_wait_event(&wq, &__wait, state);\
\
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 47c4d62..61dcee1 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -196,14 +196,20 @@ prepare_to_wait_exclusive(wait_queue_head_t *q, wait_queue_t *wait, int state)
}
EXPORT_SYMBOL(prepare_to_wait_exclusive);

+void init_wait_entry(wait_queue_t *wait, int flags)
+{
+ wait->flags = flags;
+ wait->private = current;
+ wait->func = autoremove_wake_function;
+ INIT_LIST_HEAD(&wait->task_list);
+}
+EXPORT_SYMBOL(init_wait_entry);
+
long prepare_to_wait_event(wait_queue_head_t *q, wait_queue_t *wait, int state)
{
unsigned long flags;
long ret = 0;

- wait->private = current;
- wait->func = autoremove_wake_function;
-
spin_lock_irqsave(&q->lock, flags);
if (unlikely(signal_pending_state(state, current))) {
/*
--
2.5.0
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