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block: document blk_plug list access 

I'm often confused why not disable preempt when changing blk_plug list. It
would be better to add comments here in case others have the similar concerns.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
hifive-unleashed-5.1
Shaohua Li 2011-07-08 08:19:21 +02:00 committed by Jens Axboe
parent 55c022bbdd
commit 316cc67d5e
1 changed files with 6 additions and 0 deletions
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6
include/linux/blkdev.h
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@ -857,6 +857,12 @@ struct request_queue *blk_alloc_queue(gfp_t);
struct request_queue *blk_alloc_queue_node(gfp_t, int);
extern void blk_put_queue(struct request_queue *);
/*
* Note: Code in between changing the blk_plug list/cb_list or element of such
* lists is preemptable, but such code can't do sleep (or be very careful),
* otherwise data is corrupted. For details, please check schedule() where
* blk_schedule_flush_plug() is called.
*/
struct blk_plug {
unsigned long magic;
struct list_head list;