* Re: [PATCH] cfs: NULL pointer check
2011-09-16 17:48 [PATCH] cfs: NULL pointer check Wang Xingchao
@ 2011-09-16 5:57 ` Yong Zhang
2011-09-16 7:42 ` Paul Turner
1 sibling, 0 replies; 4+ messages in thread
From: Yong Zhang @ 2011-09-16 5:57 UTC (permalink / raw)
To: Wang Xingchao; +Cc: linux-kernel, mingo, peterz, alex.shi
On Fri, Sep 16, 2011 at 01:48:53PM -0400, Wang Xingchao wrote:
> se maybe NULL if cfs_rq->rb_leftmost is NULL
I don't think se could be NULL here. Because we call check_preempt_tick()
iff 'cfs_rq->nr_running > 1'.
Thanks,
Yong
>
> Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
> ---
> kernel/sched_fair.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index fef0bfd..109b232 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1130,6 +1130,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> return;
>
> se = __pick_first_entity(cfs_rq);
> +
> + if (!se)
> + return;
> +
> delta = curr->vruntime - se->vruntime;
>
> if (delta < 0)
> --
> 1.7.1
>
> --
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] cfs: NULL pointer check
2011-09-16 17:48 [PATCH] cfs: NULL pointer check Wang Xingchao
2011-09-16 5:57 ` Yong Zhang
@ 2011-09-16 7:42 ` Paul Turner
2011-09-16 21:18 ` xingchao
1 sibling, 1 reply; 4+ messages in thread
From: Paul Turner @ 2011-09-16 7:42 UTC (permalink / raw)
To: Wang Xingchao; +Cc: linux-kernel, mingo, peterz, yong.zhang0, alex.shi
On 09/16/11 10:48, Wang Xingchao wrote:
> se maybe NULL if cfs_rq->rb_leftmost is NULL
nack, it had better not be; otherwise we've got a corrupt tree!
Also, this diff is against the previous -- please bundle dependent
patches as a series in the future.
Thanks,
- Paul
>
> Signed-off-by: Wang Xingchao<xingchao.wang@intel.com>
> ---
> kernel/sched_fair.c | 4 ++++
> 1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index fef0bfd..109b232 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -1130,6 +1130,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
> return;
>
> se = __pick_first_entity(cfs_rq);
> +
> + if (!se)
> + return;
> +
> delta = curr->vruntime - se->vruntime;
>
> if (delta< 0)
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] cfs: NULL pointer check
@ 2011-09-16 17:48 Wang Xingchao
2011-09-16 5:57 ` Yong Zhang
2011-09-16 7:42 ` Paul Turner
0 siblings, 2 replies; 4+ messages in thread
From: Wang Xingchao @ 2011-09-16 17:48 UTC (permalink / raw)
To: linux-kernel; +Cc: mingo, peterz, yong.zhang0, alex.shi, Wang Xingchao
se maybe NULL if cfs_rq->rb_leftmost is NULL
Signed-off-by: Wang Xingchao <xingchao.wang@intel.com>
---
kernel/sched_fair.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index fef0bfd..109b232 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1130,6 +1130,10 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
return;
se = __pick_first_entity(cfs_rq);
+
+ if (!se)
+ return;
+
delta = curr->vruntime - se->vruntime;
if (delta < 0)
--
1.7.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] cfs: NULL pointer check
2011-09-16 7:42 ` Paul Turner
@ 2011-09-16 21:18 ` xingchao
0 siblings, 0 replies; 4+ messages in thread
From: xingchao @ 2011-09-16 21:18 UTC (permalink / raw)
To: Paul Turner
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, peterz@infradead.org,
yong.zhang0@gmail.com, Shi, Alex
On Fri, 16 Sep 2011 15:42:41 +0800
Paul Turner <pjt@google.com> wrote:
> On 09/16/11 10:48, Wang Xingchao wrote:
> > se maybe NULL if cfs_rq->rb_leftmost is NULL
>
> nack, it had better not be; otherwise we've got a corrupt tree!
>
> Also, this diff is against the previous -- please bundle dependent
> patches as a series in the future.
>
Got it. :)
Paul, i'd send another patch to remove the NULL pointer check
in __pick_first/last_entity().
--xingchao
^ permalink raw reply [flat|nested] 4+ messages in thread
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2011-09-16 17:48 [PATCH] cfs: NULL pointer check Wang Xingchao
2011-09-16 5:57 ` Yong Zhang
2011-09-16 7:42 ` Paul Turner
2011-09-16 21:18 ` xingchao
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