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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2010-04-15 23:10:42 +0200 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2010-04-30 19:15:49 +0200 |
| commit | 8795d7717c467bea7b0a0649d44a258e09f34db2 (patch) | |
| tree | 33d0dc56ef918bfc7dd615162be20e77899147c5 /kernel/lockdep.c | |
| parent | 868c522b1b75fd3fd3e6a636b4c344ac08edf13a (diff) | |
| download | lwn-8795d7717c467bea7b0a0649d44a258e09f34db2.tar.gz lwn-8795d7717c467bea7b0a0649d44a258e09f34db2.zip | |
lockdep: Fix redundant_hardirqs_on incremented with irqs enabled
When a path restore the flags while irqs are already enabled, we
update the per cpu var redundant_hardirqs_on in a racy fashion
and debug_atomic_inc() warns about this situation.
In this particular case, loosing a few hits in a stat is not a big
deal, so increment it without protection.
v2: Don't bother with disabling irq, we can miss one count in
rare situations
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'kernel/lockdep.c')
| -rw-r--r-- | kernel/lockdep.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 78325f8f1139..1b58a1bbcc87 100644 --- a/kernel/lockdep.c +++ b/kernel/lockdep.c @@ -2298,7 +2298,12 @@ void trace_hardirqs_on_caller(unsigned long ip) return; if (unlikely(curr->hardirqs_enabled)) { - debug_atomic_inc(redundant_hardirqs_on); + /* + * Neither irq nor preemption are disabled here + * so this is racy by nature but loosing one hit + * in a stat is not a big deal. + */ + this_cpu_inc(lockdep_stats.redundant_hardirqs_on); return; } /* we'll do an OFF -> ON transition: */ |