Messages in this thread Patch in this message | | | Subject | [patch]block: document blk_plug list access | From | Shaohua Li <> | Date | Fri, 08 Jul 2011 09:59:29 +0800 |
| |
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> --- include/linux/blkdev.h | 6 ++++++ 1 file changed, 6 insertions(+)
Index: linux/include/linux/blkdev.h =================================================================== --- linux.orig/include/linux/blkdev.h 2011-07-08 09:21:19.000000000 +0800 +++ linux/include/linux/blkdev.h 2011-07-08 09:34:39.000000000 +0800 @@ -857,6 +857,12 @@ struct request_queue *blk_alloc_queue(gf 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;
| |