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| author | Hugh Dickins <hughd@google.com> | 2012-02-17 13:20:31 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-02-21 15:33:34 -0800 |
| commit | 1cc85961e214773cb7d7f2ccbe3bc644dd466df0 (patch) | |
| tree | 1ded62f9f4c72a00b5cca2396919ee4c2ec547ec /kernel/rcutree.c | |
| parent | 696a02cc16b182dd78b1f395ae336f449cc90f11 (diff) | |
| download | lwn-1cc85961e214773cb7d7f2ccbe3bc644dd466df0.tar.gz lwn-1cc85961e214773cb7d7f2ccbe3bc644dd466df0.zip | |
rcu: Stop spurious warnings from synchronize_sched_expedited
synchronize_sched_expedited() is spamming CONFIG_DEBUG_PREEMPT=y
users with an unintended warning from the cpu_is_offline() check: use
raw_smp_processor_id() instead of smp_processor_id() there.
Because the warning is under a get_online_cpus(), it is not possible
for any CPUs to go offline, though it is quite possible that the
task might migrate between the raw_smp_processor_id() and the check
of cpu_is_offline(). This is not a problem because the task cannot
migrate from an offline CPU to an online one or vice versa. The point
of the check is to verify that synchronize_sched_expedited() is not
called from an offline CPU, for example, from a CPU_DYING notifier, or,
more important, from an outgoing CPU making its way from its CPU_DYING
notifiers to the idle loop.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index eacc10b03531..1050d6d3922c 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -2014,7 +2014,7 @@ void synchronize_sched_expedited(void) /* Note that atomic_inc_return() implies full memory barrier. */ firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started); get_online_cpus(); - WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); + WARN_ON_ONCE(cpu_is_offline(raw_smp_processor_id())); /* * Each pass through the following loop attempts to force a |