[tip:sched/core] sched: Pull up the might_sleep() check into cond_resched()

[tip-bot for Frederic Weisbecker <fweisbec@gmail.com>]

Commit-ID:  613afbf83298efaead05ebcac23d2285609d7160
Gitweb:     http://git.kernel.org/tip/613afbf83298efaead05ebcac23d2285609d7160
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Thu, 16 Jul 2009 15:44:29 +0200
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 18 Jul 2009 15:51:44 +0200

sched: Pull up the might_sleep() check into cond_resched()

might_sleep() is called late-ish 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.

Also define cond_resched_*() helpers as macros, so that the
FILE/LINE reported in the sleeping while atomic warning
displays the real origin and not sched.h

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.

Changes in v3:

 - Also propagate this __might_sleep() pull up to
   cond_resched_lock() and cond_resched_softirq()

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1247725694-6082-6-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
 fs/dcache.c           |    1 +
 include/linux/sched.h |   29 +++++++++++++++++++----------
 kernel/sched.c        |   12 +++++-------
 3 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 9e5cd3c..a100fa3 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -32,6 +32,7 @@
 #include <linux/swap.h>
 #include <linux/bootmem.h>
 #include <linux/fs_struct.h>
+#include <linux/hardirq.h>
 #include "internal.h"
 
 int sysctl_vfs_cache_pressure __read_mostly = 100;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e2bdf18..c41d424 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2286,17 +2286,26 @@ static inline int need_resched(void)
  */
 extern int _cond_resched(void);
 
-static inline int cond_resched(void)
-{
-	return _cond_resched();
-}
+#define cond_resched() ({			\
+	__might_sleep(__FILE__, __LINE__, 0);	\
+	_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();
-}
+extern int __cond_resched_lock(spinlock_t *lock);
+
+#define cond_resched_lock(lock) ({				\
+	__might_sleep(__FILE__, __LINE__, PREEMPT_OFFSET);	\
+	__cond_resched_lock(lock);				\
+})
+
+extern int __cond_resched_softirq(void);
+
+#define cond_resched_softirq() ({				\
+	__might_sleep(__FILE__, __LINE__, SOFTIRQ_OFFSET);	\
+	__cond_resched_softirq();				\
+})
+
+#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 3ff4d00..1f7919a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6610,8 +6610,6 @@ static inline int should_resched(void)
 
 static void __cond_resched(void)
 {
-	__might_sleep(__FILE__, __LINE__, 0);
-
 	add_preempt_count(PREEMPT_ACTIVE);
 	schedule();
 	sub_preempt_count(PREEMPT_ACTIVE);
@@ -6628,14 +6626,14 @@ int __sched _cond_resched(void)
 EXPORT_SYMBOL(_cond_resched);
 
 /*
- * cond_resched_lock() - if a reschedule is pending, drop the given lock,
+ * __cond_resched_lock() - if a reschedule is pending, drop the given lock,
  * call schedule, and on return reacquire the lock.
  *
  * This works OK both with and without CONFIG_PREEMPT. We do strange low-level
  * operations here to prevent schedule() from being called twice (once via
  * spin_unlock(), once by hand).
  */
-int cond_resched_lock(spinlock_t *lock)
+int __cond_resched_lock(spinlock_t *lock)
 {
 	int resched = should_resched();
 	int ret = 0;
@@ -6651,9 +6649,9 @@ int cond_resched_lock(spinlock_t *lock)
 	}
 	return ret;
 }
-EXPORT_SYMBOL(cond_resched_lock);
+EXPORT_SYMBOL(__cond_resched_lock);
 
-int __sched cond_resched_softirq(void)
+int __sched __cond_resched_softirq(void)
 {
 	BUG_ON(!in_softirq());
 
@@ -6665,7 +6663,7 @@ int __sched cond_resched_softirq(void)
 	}
 	return 0;
 }
-EXPORT_SYMBOL(cond_resched_softirq);
+EXPORT_SYMBOL(__cond_resched_softirq);
 
 /**
  * yield - yield the current processor to other threads.