sched: mark rwsem functions as __sched for wchan/profiling

Livio Soares · Ingo Molnar · commit c7af77b584b0 · 2007-12-18T15:21:13.000+01:00
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. [ akpm@linux-foundation.org: build fix ] Signed-off-by: Livio Soares <livio@eecg.toronto.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/rwsem.c b/kernel/rwsem.c
@@ -6,6 +6,7 @@
 
 #include <linux/types.h>
 #include <linux/kernel.h>
+#include <linux/sched.h>
 #include <linux/module.h>
 #include <linux/rwsem.h>
 
@@ -15,7 +16,7 @@
 /*
  * 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 +43,7 @@ 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_);
diff --git a/lib/rwsem.c b/lib/rwsem.c
@@ -146,7 +146,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)
 /*
  * 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)
 {

Original file line number	Diff line number	Diff line change
`@@ -146,7 +146,7 @@ __rwsem_do_wake(struct rw_semaphore *sem, int downgrading)`
`146`	`146`	`/*`
`147`	`147`	`* wait for a lock to be granted`
`148`	`148`	`*/`
`149`		`-static struct rw_semaphore *`
	`149`	`+static struct rw_semaphore __sched *`
`150`	`150`	`rwsem_down_failed_common(struct rw_semaphore *sem,`
`151`	`151`	`struct rwsem_waiter *waiter, signed long adjustment)`
`152`	`152`	`{`