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Commit 316cc67d authored by Shaohua Li's avatar Shaohua Li Committed by Jens Axboe
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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: default avatarShaohua Li <shaohua.li@intel.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 55c022bb

include/linux/blkdev.h

+6 −0
Original line number Diff line number Diff line
@@ -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;