Messages in this thread Patch in this message | | | From | Xunlei Pang <> | Subject | [PATCH v2 3/4] sched/deadline: Fix wrong cpudl_find() in check_preempt_equal_dl() | Date | Thu, 29 Jan 2015 23:53:19 +0800 |
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From: Xunlei Pang <pang.xunlei@linaro.org>
In check_preempt_equal_dl(), cpudl_find() is called with a NULL later_mask, thus cpudl_find() here doesn't check cpudl::free_cpus at all.
This patch takles this issue by always passing a non-NULL later_mask to cpudl_find(), thereby fixing this issue.
Signed-off-by: Xunlei Pang <pang.xunlei@linaro.org> --- kernel/sched/cpudeadline.c | 8 +++----- kernel/sched/deadline.c | 15 +++++++++++---- 2 files changed, 14 insertions(+), 9 deletions(-)
diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index c6acb07..f331fcf 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -97,7 +97,7 @@ static inline int cpudl_maximum(struct cpudl *cp) * cpudl_find - find the best (later-dl) CPU in the system * @cp: the cpudl max-heap context * @p: the task - * @later_mask: a mask to fill in with the selected CPUs (or NULL) + * @later_mask: a mask to fill in with the selected CPUs (not NULL) * * Returns: int - best CPU (heap maximum if suitable) */ @@ -107,15 +107,13 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, int best_cpu = -1; const struct sched_dl_entity *dl_se = &p->dl; - if (later_mask && - cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) { + if (cpumask_and(later_mask, cp->free_cpus, &p->cpus_allowed)) { best_cpu = cpumask_any(later_mask); goto out; } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) && dl_time_before(dl_se->deadline, cp->elements[0].dl)) { best_cpu = cpudl_maximum(cp); - if (later_mask) - cpumask_set_cpu(best_cpu, later_mask); + cpumask_set_cpu(best_cpu, later_mask); } out: diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index e7b2722..82d900f 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -943,14 +943,23 @@ out: return cpu; } +static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); + static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) { + struct cpumask *later_mask = + this_cpu_cpumask_var_ptr(local_cpu_mask_dl); + + /* Make sure the mask is initialized first */ + if (unlikely(!later_mask)) + return; + /* * Current can't be migrated, useless to reschedule, * let's hope p can move out. */ if (rq->curr->nr_cpus_allowed == 1 || - cpudl_find(&rq->rd->cpudl, rq->curr, NULL) == -1) + cpudl_find(&rq->rd->cpudl, rq->curr, later_mask) == -1) return; /* @@ -958,7 +967,7 @@ static void check_preempt_equal_dl(struct rq *rq, struct task_struct *p) * see if it is pushed or pulled somewhere else. */ if (p->nr_cpus_allowed != 1 && - cpudl_find(&rq->rd->cpudl, p, NULL) != -1) + cpudl_find(&rq->rd->cpudl, p, later_mask) != -1) return; resched_curr(rq); @@ -1145,8 +1154,6 @@ next_node: return NULL; } -static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask_dl); - static int find_later_rq(struct task_struct *task) { struct sched_domain *sd; -- 1.9.1
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