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authorJohannes Berg <johannes@sipsolutions.net>2007-11-14 20:00:16 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 21:45:43 -0500
commit60a0d23386eab0559ad32ae50b200cc58545f327 (patch)
treee80067693fe0600ae8cbb0b550b84ab22f43c4fe
parentc642b8391cf8efc3622cc97329a0f46e7cbb70b8 (diff)
hibernate: fix lockdep report
Lockdep reports a circular locking dependency in the hibernate code because - during system boot hibernate code (from an initcall) locks pm_mutex and then a sysfs buffer mutex via name_to_dev_t - during regular operation hibernate code locks pm_mutex under a sysfs buffer mutex because it's called from sysfs methods. The deadlock can never happen because during initcall invocation nothing can write to sysfs yet. This removes the lockdep report by marking the initcall locking as being in a different class. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Alan Stern <stern@rowland.harvard.edu> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/power/disk.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index 8b15f777010a..05b64790fe83 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -456,7 +456,17 @@ static int software_resume(void)
456 int error; 456 int error;
457 unsigned int flags; 457 unsigned int flags;
458 458
459 mutex_lock(&pm_mutex); 459 /*
460 * name_to_dev_t() below takes a sysfs buffer mutex when sysfs
461 * is configured into the kernel. Since the regular hibernate
462 * trigger path is via sysfs which takes a buffer mutex before
463 * calling hibernate functions (which take pm_mutex) this can
464 * cause lockdep to complain about a possible ABBA deadlock
465 * which cannot happen since we're in the boot code here and
466 * sysfs can't be invoked yet. Therefore, we use a subclass
467 * here to avoid lockdep complaining.
468 */
469 mutex_lock_nested(&pm_mutex, SINGLE_DEPTH_NESTING);
460 if (!swsusp_resume_device) { 470 if (!swsusp_resume_device) {
461 if (!strlen(resume_file)) { 471 if (!strlen(resume_file)) {
462 mutex_unlock(&pm_mutex); 472 mutex_unlock(&pm_mutex);