Mark rwsem functions as __sched for wchan/profiling

Hi,

This following commit

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=fdf8cb0909b531f9ae8f9b9d7e4eb35ba3505f07

un-inlined a low-level rwsem function, but did not mark it as
__sched. The result is that it now shows up as thread wchan (which also affects /proc/profile stats). The following simple patch fixes this by properly marking rwsem_down_failed_common() as a __sched function.

Also in this patch, which is up for discussion, marks down_read() and
down_write() proper as __sched. For profiling, it is pretty much useless to know that a semaphore is beig help - it is necessary to know _which_ one. By going up another frame on the stack, the information becomes much more useful.

In summary, the below change to lib/rwsem.c should be applied; the
changes to kernel/rwsem.c could be applied if other kernel hackers agree with my proposal that down_read()/down_write() in the profile is not enough.

Cheers,

Livio

 kernel/rwsem.c |    4 ++--
 lib/rwsem.c    |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

@@ -146,7 +146,7 @@ __rwsem_do_wake(struct rw_semaphore *sem
 /*
  * wait for a lock to be granted
  */
-static struct rw_semaphore *
+static struct rw_semaphore __sched *
 rwsem_down_failed_common(struct rw_semaphore *sem,
 			struct rwsem_waiter *waiter, signed long adjustment)
 {

@@ -15,7 +15,7 @@
 /*
  * lock for reading
  */
-void down_read(struct rw_semaphore *sem)
+void __sched down_read(struct rw_semaphore *sem)
 {
 	might_sleep();
 	rwsem_acquire_read(&sem->dep_map, 0, 0, _RET_IP_);

@@ -42,7 +42,7 @@ EXPORT_SYMBOL(down_read_trylock);
 /*
  * lock for writing
  */
-void down_write(struct rw_semaphore *sem)
+void __sched down_write(struct rw_semaphore *sem)
 {
 	might_sleep();
 	rwsem_acquire(&sem->dep_map, 0, 0, _RET_IP_);