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author | NeilBrown <neilb@suse.de> | 2011-04-11 12:13:10 (GMT) |
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committer | Jens Axboe <jaxboe@fusionio.com> | 2011-04-11 12:13:10 (GMT) |
commit | 109b81296c63228578d4760794d8dd46e02eddfb (patch) | |
tree | 2f723e1b69ab08e12528f677f04edbfc7473b7c5 /include/trace | |
parent | 4263a2f1dad8c8e7ce2352a0cbc882c2b0c044a9 (diff) | |
download | linux-109b81296c63228578d4760794d8dd46e02eddfb.tar.xz |
block: splice plug list to local context
If the request_fn ends up blocking, we could be re-entering
the plug flush. Since the list is protected by explicitly
not allowing schedule events, this isn't a terribly good idea.
Additionally, it can cause us to recurse. As request_fn called by
__blk_run_queue is allowed to 'schedule()' (after dropping the queue
lock of course), it is possible to get a recursive call:
schedule -> blk_flush_plug -> __blk_finish_plug -> flush_plug_list
-> __blk_run_queue -> request_fn -> schedule
We must make sure that the second schedule does not call into
blk_flush_plug again. So instead of leaving the list of requests on
blk_plug->list, move them to a separate list leaving blk_plug->list
empty.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'include/trace')
0 files changed, 0 insertions, 0 deletions