[PATCH] lockdep: core, fix rq-lock handling on __ARCH_WANT_UNLOCKED_CTXSW
On platforms that have __ARCH_WANT_UNLOCKED_CTXSW set and want to implement
lock validator support there's a bug in rq->lock handling: in this case we
dont 'carry over' the runqueue lock into another task - but still we did a
spinlock_release() of it. Fix this by making the spinlock_release() in
context_switch() dependent on !__ARCH_WANT_UNLOCKED_CTXSW.
(Reported by Ralf Baechle on MIPS, which has __ARCH_WANT_UNLOCKED_CTXSW.
This fixes a lockdep-internal BUG message on such platforms.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/sched.c b/kernel/sched.c
index d714611..e9a0b61 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1788,7 +1788,15 @@
WARN_ON(rq->prev_mm);
rq->prev_mm = oldmm;
}
+ /*
+ * Since the runqueue lock will be released by the next
+ * task (which is an invalid locking op but in the case
+ * of the scheduler it's an obvious special-case), so we
+ * do an early lockdep release here:
+ */
+#ifndef __ARCH_WANT_UNLOCKED_CTXSW
spin_release(&rq->lock.dep_map, 1, _THIS_IP_);
+#endif
/* Here we just switch the register state and the stack. */
switch_to(prev, next, prev);
