| commit | 62c1fe9d9f0a676fce89185b1513f0e5f473c72c | |
| author | Jens Axboe <jens.axboe@oracle.com> | |
| Mon, 15 Dec 2008 20:19:25 +0000 (15 21:19 +0100) | ||
| committer | Jens Axboe <jens.axboe@oracle.com> | |
| Mon, 29 Dec 2008 07:29:52 +0000 (29 08:29 +0100) | ||
| tree | 28085a657fa93ed63b7dda20b5a84885e67d429e | treesnapshot (tar.gz zip) |
| parent | 8ae30b895805a6e2bb725b1d78b12daabd7eadfe | commitdiff |
cfq-iosched: fix race between exiting queue and exiting task
Original patch from Nikanth Karthikesan <knikanth@suse.de>
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 <jens.axboe@oracle.com>
Original patch from Nikanth Karthikesan <knikanth@suse.de>
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 <jens.axboe@oracle.com>
| block/cfq-iosched.c | diffblobblamehistory |