Revision 4cdd2ad78098244c1bc9ec4374ea1c225fd1cd6f authored by Mike Snitzer on 13 May 2014, 17:49:39 UTC, committed by Mike Snitzer on 14 May 2014, 20:12:17 UTC
Commit 3e9f1be1b40 ("dm mpath: remove process_queued_ios()") did not
consistently take the multipath device's spinlock (m->lock) before
calling dm_table_run_md_queue_async() -- which takes the q->queue_lock.

Found with code inspection using hint from reported lockdep warning.

Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1 parent 85ad643
Raw File
debug_locks.c
/*
 * lib/debug_locks.c
 *
 * Generic place for common debugging facilities for various locks:
 * spinlocks, rwlocks, mutexes and rwsems.
 *
 * Started by Ingo Molnar:
 *
 *  Copyright (C) 2006 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
 */
#include <linux/rwsem.h>
#include <linux/mutex.h>
#include <linux/export.h>
#include <linux/spinlock.h>
#include <linux/debug_locks.h>

/*
 * We want to turn all lock-debugging facilities on/off at once,
 * via a global flag. The reason is that once a single bug has been
 * detected and reported, there might be cascade of followup bugs
 * that would just muddy the log. So we report the first one and
 * shut up after that.
 */
int debug_locks = 1;
EXPORT_SYMBOL_GPL(debug_locks);

/*
 * The locking-testsuite uses <debug_locks_silent> to get a
 * 'silent failure': nothing is printed to the console when
 * a locking bug is detected.
 */
int debug_locks_silent;
EXPORT_SYMBOL_GPL(debug_locks_silent);

/*
 * Generic 'turn off all lock debugging' function:
 */
int debug_locks_off(void)
{
	if (__debug_locks_off()) {
		if (!debug_locks_silent) {
			console_verbose();
			return 1;
		}
	}
	return 0;
}
EXPORT_SYMBOL_GPL(debug_locks_off);
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