Messages in this thread Patch in this message | | | Date | Fri, 30 Apr 2021 09:40:48 +0000 | From | Quentin Perret <> | Subject | Re: [PATCH v2] sched: Fix out-of-bound access in uclamp |
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On Friday 30 Apr 2021 at 10:49:50 (+0200), Vincent Guittot wrote: > 20 buckets is probably not the best example because of the rounding of > the division. With 16 buckets, each bucket should be exactly 64 steps > large except the last one which will have 65 steps because of the > value 1024. With your change, buckets will be 65 large and the last > one will be only 49 large
OK, so what do you think of this?
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c5fb230dc604..dceeb5821797 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -920,14 +920,14 @@ static struct uclamp_se uclamp_default[UCLAMP_CNT]; */ DEFINE_STATIC_KEY_FALSE(sched_uclamp_used);
-#define UCLAMP_BUCKET_DELTA (SCHED_CAPACITY_SCALE / UCLAMP_BUCKETS + 1) +#define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS)
#define for_each_clamp_id(clamp_id) \ for ((clamp_id) = 0; (clamp_id) < UCLAMP_CNT; (clamp_id)++)
static inline unsigned int uclamp_bucket_id(unsigned int clamp_value) { - return clamp_value / UCLAMP_BUCKET_DELTA; + return min(clamp_value / UCLAMP_BUCKET_DELTA, UCLAMP_BUCKETS - 1); }
static inline unsigned int uclamp_none(enum uclamp_id clamp_id)
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