From: Con Kolivas Use of memset was bogus. Fix it. Fix exiting recalc_task_prio without p->array being updated. Microoptimisation courtesy of Dmitry Adamushko Signed-off-by: Con Kolivas Signed-off-by: Andrew Morton --- kernel/sched.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff -puN kernel/sched.c~sched-implement-staircase-deadline-cpu-scheduler-improvements-fix kernel/sched.c --- a/kernel/sched.c~sched-implement-staircase-deadline-cpu-scheduler-improvements-fix +++ a/kernel/sched.c @@ -683,11 +683,13 @@ static void dequeue_task(struct task_str * The task is being queued on a fresh array so it has its entitlement * bitmap cleared. */ -static inline void task_new_array(struct task_struct *p, struct rq *rq) +static void task_new_array(struct task_struct *p, struct rq *rq, + struct prio_array *array) { bitmap_zero(p->bitmap, PRIO_RANGE); p->rotation = rq->prio_rotation; p->time_slice = p->quota; + p->array = array; } /* Find the first slot from the relevant prio_matrix entry */ @@ -709,6 +711,8 @@ static inline int next_entitled_slot(str DECLARE_BITMAP(tmp, PRIO_RANGE); int search_prio, uprio = USER_PRIO(p->static_prio); + if (!rq->prio_level[uprio]) + rq->prio_level[uprio] = MAX_RT_PRIO; /* * Only priorities equal to the prio_level and above for their * static_prio are acceptable, and only if it's not better than @@ -736,11 +740,8 @@ static inline int next_entitled_slot(str static void queue_expired(struct task_struct *p, struct rq *rq) { - p->array = rq->expired; - task_new_array(p, rq); + task_new_array(p, rq, rq->expired); p->prio = p->normal_prio = first_prio_slot(p); - p->time_slice = p->quota; - p->rotation = rq->prio_rotation; } #ifdef CONFIG_SMP @@ -800,9 +801,9 @@ static void recalc_task_prio(struct task queue_expired(p, rq); return; } else - task_new_array(p, rq); + task_new_array(p, rq, array); } else - task_new_array(p, rq); + task_new_array(p, rq, array); queue_prio = next_entitled_slot(p, rq); if (queue_prio >= MAX_PRIO) { @@ -3445,7 +3446,7 @@ EXPORT_SYMBOL(sub_preempt_count); static inline void reset_prio_levels(struct rq *rq) { - memset(rq->prio_level, MAX_RT_PRIO, ARRAY_SIZE(rq->prio_level)); + memset(rq->prio_level, 0, sizeof(int) * PRIO_RANGE); } /* _