Messages in this thread | | | From | Paul Turner <> | Date | Tue, 13 Dec 2011 04:40:03 -0800 | Subject | Re: [PATCH tip] sched/trivial: Remove cfs bandwidth period check in tg_set_cfs_period() |
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On Mon, Dec 12, 2011 at 5:05 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > On Sat, 2011-12-10 at 19:29 +0530, Kamalesh Babulal wrote: >> sched: Remove cfs bandwidth period check in tg_set_cfs_period() >> >> Remove cfs bandwidth period check from tg_set_cfs_period. >> Invalid bandwidth period's lower/upper limits are denoted >> by min_cfs_quota_period/max_cfs_quota_period repsectively, >> and are checked against valid period in tg_set_cfs_bandwidth(). >> >> Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com> >> -- >> kernel/sched/core.c | 3 --- >> 1 files changed, 0 insertions(+), 3 deletions(-) >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 3c5b21e..57cf3ab 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -7689,9 +7689,6 @@ int tg_set_cfs_period(struct task_group *tg, long cfs_period_us) >> period = (u64)cfs_period_us * NSEC_PER_USEC; >> quota = tg->cfs_bandwidth.quota; >> >> - if (period <= 0) >> - return -EINVAL; >> - >> return tg_set_cfs_bandwidth(tg, period, quota); >> } > > There's a number of funnies here... it checks an unsigned value for <= > 0, which suggests it wanted to check cfs_period_us, which is a signed > value.
Yup it wanted to check cfs_period0us -- although as Kamelesh points out, it can be omitted.
> > tg_set_cfs_bandwidth() has the same problem, at that point everything is > unsigned and all below zero checks will fail. > > Please reconsider things and see if this patch is still the right one.
It's OK though since period is always strictly unsigned so any -ve becomes larger than the max allowed period and it spits out -EINVAL as appropriate.
So Kamelesh's patch above is good as is.
Acked-by: Paul Turner <pjt@google.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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