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SubjectRe: [PATCH 1/1] scheduler: access to variable out of scope in sched_slice()

* Christian Engelmayer <christian.engelmayer@frequentis.com> wrote:

> From: Christian Engelmayer <christian.engelmayer@frequentis.com>
>
> Access to local variable lw is aliased by usage of pointer load. Access to
> pointer load in calc_delta_mine() happens when lw is already out of scope.
>
> Signed-off-by: Christian Engelmayer <christian.engelmayer@frequentis.com>
> --
> Reported by static code analysis.
>
> --- linux-2.6.30/kernel/sched_fair.c.orig 2009-06-16 10:01:50.000000000 +0200
> +++ linux-2.6.30/kernel/sched_fair.c 2009-06-16 10:02:39.000000000 +0200
> @@ -430,12 +430,13 @@ static u64 sched_slice(struct cfs_rq *cf
>
> for_each_sched_entity(se) {
> struct load_weight *load;
> + struct load_weight lw;
>
> cfs_rq = cfs_rq_of(se);
> load = &cfs_rq->load;
>
> if (unlikely(!se->on_rq)) {
> - struct load_weight lw = cfs_rq->load;
> + lw = cfs_rq->load;
>
> update_load_add(&lw, se->load.weight);
> load = &lw;

Good one!

I suspect it doesnt matter in practice because GCC will just have
them all on the same stack frame?

Ingo


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