From: Tejun Heo Date: Fri, 2 Jul 2010 08:03:51 +0000 (+0200) Subject: workqueue: fix race condition in flush_workqueue() X-Git-Tag: v2.6.36-rc1~506^2~21 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ce48b37bfedc2bc11e61eae76784887e88b922c;p=pandora-kernel.git workqueue: fix race condition in flush_workqueue() When one flusher is cascading to the next flusher, it first sets wq->first_flusher to the next one and sets up the next flush cycle. If there's nothing to do for the next cycle, it clears wq->flush_flusher and proceeds to the one after that. If the woken up flusher checks wq->first_flusher before it gets cleared, it will incorrectly assume the role of the first flusher, which triggers BUG_ON() sanity check. Fix it by checking wq->first_flusher again after grabbing the mutex. Signed-off-by: Tejun Heo --- Reading git-diff-tree failed