From: Jens Axboe Date: Mon, 15 Dec 2008 20:19:25 +0000 (+0100) Subject: cfq-iosched: fix race between exiting queue and exiting task X-Git-Tag: v2.6.29-rc1~569^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=62c1fe9d9f0a676fce89185b1513f0e5f473c72c;p=pandora-kernel.git cfq-iosched: fix race between exiting queue and exiting task Original patch from Nikanth Karthikesan When a queue exits the queue lock is taken and cfq_exit_queue() would free all the cic's associated with the queue. But when a task exits, cfq_exit_io_context() gets cic one by one and then locks the associated queue to call __cfq_exit_single_io_context. It looks like between getting a cic from the ioc and locking the queue, the queue might have exited on another cpu. Fix this by rechecking the cfq_io_context queue key inside the queue lock again, and not calling into __cfq_exit_single_io_context() if somebody beat us to it. Signed-off-by: Jens Axboe --- Reading git-diff-tree failed