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scsi: sg: update comment for blk_get_request() 

The calling convention of blk_get_request() has changed in lk 4.18; update
the comment in sg.c to match.

Fixes: ff005a0662 ("block: sanitize blk_get_request calling conventions")
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Tony Battersby 2018-07-12 18:09:21 -04:00 committed by Martin K. Petersen
parent c170e5a8d2
commit 8e4a4189ce
1 changed files with 5 additions and 9 deletions
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14
drivers/scsi/sg.c
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@ -1741,15 +1741,11 @@ sg_start_req(Sg_request *srp, unsigned char *cmd)
*
* With scsi-mq enabled, there are a fixed number of preallocated
* requests equal in number to shost->can_queue. If all of the
* preallocated requests are already in use, then using GFP_ATOMIC with
* blk_get_request() will return -EWOULDBLOCK, whereas using GFP_KERNEL
* will cause blk_get_request() to sleep until an active command
* completes, freeing up a request. Neither option is ideal, but
* GFP_KERNEL is the better choice to prevent userspace from getting an
* unexpected EWOULDBLOCK.
*
* With scsi-mq disabled, blk_get_request() with GFP_KERNEL usually
* does not sleep except under memory pressure.
* preallocated requests are already in use, then blk_get_request()
* will sleep until an active command completes, freeing up a request.
* Although waiting in an asynchronous interface is less than ideal, we
* do not want to use BLK_MQ_REQ_NOWAIT here because userspace might
* not expect an EWOULDBLOCK from this condition.
*/
rq = blk_get_request(q, hp->dxfer_direction == SG_DXFER_TO_DEV ?
REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, 0);