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>
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 @@
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: */