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| author | Mohammed Khajapasha <mkhaja@codeaurora.org> | 2017-07-07 13:06:00 +0530 |
|---|---|---|
| committer | Mohammed Khajapasha <mkhaja@codeaurora.org> | 2017-07-07 15:20:34 +0530 |
| commit | 131e4378a0d7ae16ca61c0364ff35d987e782254 (patch) | |
| tree | de555b0a479dc6b643776491c181d25247b9b267 /kernel/cpu.c | |
| parent | 0c44f3c838e32d6c4928a3d175b5406b4b4af293 (diff) | |
Revert "sched: Remove synchronize rcu/sched calls from _cpu_down"
This reverts commit 36131fdc87c8 ("sched: Remove synchronize
rcu/sched calls from _cpu_down").
Removing the synchronization of rcu/sched calls from _cpu_down
introduces a race where tasks may get queued on an inactive CPU
and unthrottling cfs_rqs.
Change-Id: Ie29f8d185eb55979f9ca4e6e1b767caba6dd7f27
Signed-off-by: Mohammed Khajapasha <mkhaja@codeaurora.org>
Diffstat (limited to 'kernel/cpu.c')
| -rw-r--r-- | kernel/cpu.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/kernel/cpu.c b/kernel/cpu.c index 1a26ef5b7d58..87b88e8c0233 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -375,6 +375,21 @@ static int _cpu_down(unsigned int cpu, int tasks_frozen) goto out_release; } + /* + * By now we've cleared cpu_active_mask, wait for all preempt-disabled + * and RCU users of this state to go away such that all new such users + * will observe it. + * + * For CONFIG_PREEMPT we have preemptible RCU and its sync_rcu() might + * not imply sync_sched(), so wait for both. + * + * Do sync before park smpboot threads to take care the rcu boost case. + */ + if (IS_ENABLED(CONFIG_PREEMPT)) + synchronize_rcu_mult(call_rcu, call_rcu_sched); + else + synchronize_rcu(); + smpboot_park_threads(cpu); /* |