Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 1/2 v2] lockdep: Fix redundant_hardirqs_on incremented with irqs enabled | Date | Thu, 15 Apr 2010 23:10:42 +0200 |
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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> --- kernel/lockdep.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)
diff --git a/kernel/lockdep.c b/kernel/lockdep.c index 78325f8..1b58a1b 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: */ -- 1.6.2.3
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