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author | Ingo Molnar <mingo@elte.hu> | 2010-02-08 07:55:43 (GMT) |
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committer | Ingo Molnar <mingo@elte.hu> | 2010-02-08 07:55:46 (GMT) |
commit | 6d3e0907b8b239d16720d144e2675ecf10d3bc3b (patch) | |
tree | e0b0743b5f6f82b057cafc4f3687396a6e01a0b4 /kernel/sched.c | |
parent | 23577256953c870de9b724c3a2611ce7be6a1e4e (diff) | |
parent | 50200df462023b187d80a99a52f5f2cfe3c86c26 (diff) | |
download | linux-6d3e0907b8b239d16720d144e2675ecf10d3bc3b.tar.xz |
Merge branch 'sched/urgent' into sched/core
Merge reason: Merge dependent fix, update to latest -rc.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched.c')
-rw-r--r-- | kernel/sched.c | 44 |
1 files changed, 31 insertions, 13 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index 6cee227..f96be93 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2286,14 +2286,12 @@ static int select_fallback_rq(int cpu, struct task_struct *p) } /* - * Called from: + * Gets called from 3 sites (exec, fork, wakeup), since it is called without + * holding rq->lock we need to ensure ->cpus_allowed is stable, this is done + * by: * - * - fork, @p is stable because it isn't on the tasklist yet - * - * - exec, @p is unstable, retry loop - * - * - wake-up, we serialize ->cpus_allowed against TASK_WAKING so - * we should be good. + * exec: is unstable, retry loop + * fork & wake-up: serialize ->cpus_allowed against TASK_WAKING */ static inline int select_task_rq(struct task_struct *p, int sd_flags, int wake_flags) @@ -2586,9 +2584,6 @@ void sched_fork(struct task_struct *p, int clone_flags) if (p->sched_class->task_fork) p->sched_class->task_fork(p); -#ifdef CONFIG_SMP - cpu = select_task_rq(p, SD_BALANCE_FORK, 0); -#endif set_task_cpu(p, cpu); #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) @@ -2618,6 +2613,21 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) { unsigned long flags; struct rq *rq; + int cpu __maybe_unused = get_cpu(); + +#ifdef CONFIG_SMP + /* + * Fork balancing, do it here and not earlier because: + * - cpus_allowed can change in the fork path + * - any previously selected cpu might disappear through hotplug + * + * We still have TASK_WAKING but PF_STARTING is gone now, meaning + * ->cpus_allowed is stable, we have preemption disabled, meaning + * cpu_online_mask is stable. + */ + cpu = select_task_rq(p, SD_BALANCE_FORK, 0); + set_task_cpu(p, cpu); +#endif rq = task_rq_lock(p, &flags); BUG_ON(p->state != TASK_WAKING); @@ -2631,6 +2641,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) p->sched_class->task_woken(rq, p); #endif task_rq_unlock(rq, &flags); + put_cpu(); } #ifdef CONFIG_PREEMPT_NOTIFIERS @@ -3687,8 +3698,11 @@ need_resched_nonpreemptible: post_schedule(rq); - if (unlikely(reacquire_kernel_lock(current) < 0)) + if (unlikely(reacquire_kernel_lock(current) < 0)) { + prev = rq->curr; + switch_count = &prev->nivcsw; goto need_resched_nonpreemptible; + } preempt_enable_no_resched(); if (need_resched()) @@ -5293,14 +5307,18 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask) * the ->cpus_allowed mask from under waking tasks, which would be * possible when we change rq->lock in ttwu(), so synchronize against * TASK_WAKING to avoid that. + * + * Make an exception for freshly cloned tasks, since cpuset namespaces + * might move the task about, we have to validate the target in + * wake_up_new_task() anyway since the cpu might have gone away. */ again: - while (p->state == TASK_WAKING) + while (p->state == TASK_WAKING && !(p->flags & PF_STARTING)) cpu_relax(); rq = task_rq_lock(p, &flags); - if (p->state == TASK_WAKING) { + if (p->state == TASK_WAKING && !(p->flags & PF_STARTING)) { task_rq_unlock(rq, &flags); goto again; } |