Commit 3a5f5e48 authored Jul 14, 2006 by Ingo Molnar Committed by Linus Torvalds Jul 14, 2006

[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>

parent 2e8f7a31

kernel/sched.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -1788,7 +1788,15 @@ context_switch(struct rq rq, struct task_struct prev,
		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);

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