[PATCH -tip] sched: fix using uninilialzed rq in task_delta_exec()

[PATCH -tip] sched: fix using uninilialzed rq in task_delta_exec()

[Hiroshi Shimamoto]

From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>

compiler warnings;

  CC      kernel/sched.o
kernel/sched.c: In function 'task_delta_exec':
kernel/sched.c:4055: warning: unused variable 'flags'
kernel/sched.c:4054: warning: 'rq' is used uninitialized in this function

calling task_delta_exec() may cause unexpected pointer access.

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
---
 kernel/sched.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 30b73fc..b6c0dd8 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4055,6 +4055,7 @@ unsigned long long task_delta_exec(struct task_struct *p)
 	unsigned long flags;
 	u64 ns = 0;
 
+	rq = task_rq_lock(p, &flags);
 	if (task_current(rq, p)) {
 		u64 delta_exec;
 
@@ -4063,6 +4064,7 @@ unsigned long long task_delta_exec(struct task_struct *p)
 		if ((s64)delta_exec > 0)
 			ns = delta_exec;
 	}
+	task_rq_unlock(rq, &flags);
 
 	return ns;
 }
-- 
1.5.6

Re: [PATCH -tip] sched: fix using uninilialzed rq in task_delta_exec()

[Ingo Molnar]

* Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> wrote:

> From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
> 
> compiler warnings;
> 
>   CC      kernel/sched.o
> kernel/sched.c: In function 'task_delta_exec':
> kernel/sched.c:4055: warning: unused variable 'flags'
> kernel/sched.c:4054: warning: 'rq' is used uninitialized in this function
> 
> calling task_delta_exec() may cause unexpected pointer access.

heh, just fixed that as well, latest tip/master should have the fix.

Have you seen any weirdness due to this uninitialized variable?

	Ingo

Re: [PATCH -tip] sched: fix using uninilialzed rq in task_delta_exec()

[Hiroshi Shimamoto]

Ingo Molnar wrote:
> * Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> wrote:
> 
>> From: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
>>
>> compiler warnings;
>>
>>   CC      kernel/sched.o
>> kernel/sched.c: In function 'task_delta_exec':
>> kernel/sched.c:4055: warning: unused variable 'flags'
>> kernel/sched.c:4054: warning: 'rq' is used uninitialized in this function
>>
>> calling task_delta_exec() may cause unexpected pointer access.
> 
> heh, just fixed that as well, latest tip/master should have the fix.
> 
> Have you seen any weirdness due to this uninitialized variable?

No I've never seen any problem yesterday.
And I didn't have much time to use tip tree yesterday:)

Today's looks good.

thanks,
Hiroshi Shimamoto