[PATCH] sched: Move the sleeping while atomic checks early in cond_resched()

Frederic Weisbecker
2009-07-10T17:15:20Z

might_sleep() is called lately in cond_resched(), after the
need_resched()/preempt enabled/system running tests are checked.

It's better to check the sleeps while atomic earlier and not depend
on some environment datas that reduce the chances to detect a
problem.

Changes in v2:
- call __might_sleep() directly instead of might_sleep() which may call
cond_resched()
- turn cond_resched() into a macro so that the file:line couple reported
refers to the caller of cond_resched() and not __cond_resched() itself.
- drop the obsolete CONFIG_PREEMPT_BKL related zones

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
---
include/linux/sched.h | 22 +++++++---------------
kernel/sched.c | 5 ++---
2 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 0cb0d8d..737f569 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2276,23 +2276,15 @@ static inline int need_resched(void)
* cond_resched_softirq() will enable bhs before scheduling.
*/
extern int _cond_resched(void);
-#ifdef CONFIG_PREEMPT_BKL
-static inline int cond_resched(void)
-{
- return 0;
-}
-#else
-static inline int cond_resched(void)
-{
- return _cond_resched();
-}
-#endif
+#define cond_resched() ({ \
+ __might_sleep(__FILE__, __LINE__); \
+ _cond_resched(); \
+})
+
extern int cond_resched_lock(spinlock_t * lock);
extern int cond_resched_softirq(void);
-static inline int cond_resched_bkl(void)
-{
- return _cond_resched();
-}
+
+#define cond_resched_bkl() cond_resched();

/*
* Does a critical section need to be broken due to another
diff --git a/kernel/sched.c b/kernel/sched.c
index 87ecac1..649ec92 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6605,9 +6605,6 @@ SYSCALL_DEFINE0(sched_yield)

static void __cond_resched(void)
{
-#ifdef CONFIG_DEBUG_SPINLOCK_SLEEP
- __might_sleep(__FILE__, __LINE__);
-#endif
/*
* The BKS might be reacquired before we have dropped
* PREEMPT_ACTIVE, which could trigger a second
@@ -6644,6 +6641,7 @@ int cond_resched_lock(spinlock_t *lock)

if (spin_needbreak(lock) || resched) {
spin_unlock(lock);
+ __might_sleep(__FILE__, __LINE__);
if (resched && need_resched())
__cond_resched();
else
@@ -6661,6 +6659,7 @@ int __sched cond_resched_softirq(void)

if (need_resched() && system_state == SYSTEM_RUNNING) {
local_bh_enable();
+ __might_sleep(__FILE__, __LINE__);
__cond_resched();
local_bh_disable();
return 1;
--
1.6.2.3