block,scsi: fixup blk_get_request dead queue scenarios

The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
ERR_PTR. Verify that all callers check the return status and consider
IS_ERR instead of a simple NULL pointer check.

For consistency, make a similar change to the blk_mq_alloc_request leg
of blk_get_request.  It may fail if the queue is dead, or the caller was
unwilling to wait.

Signed-off-by: Joe Lawrence <[email protected]>
Acked-by: Jiri Kosina <[email protected]> [for pktdvd]
Acked-by: Boaz Harrosh <[email protected]> [for osd]
Reviewed-by: Jeff Moyer <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Joe Lawrence 2014-08-28 08:15:21 -06:00 • committed by Jens Axboe
commit a492f07545
20 changed files with 55 additions and 51 deletions

View file

@ -270,8 +270,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
* map scatter-gather elements separately and string them to request
*/
rq = blk_get_request(q, rw, GFP_KERNEL);
if (!rq)
return ERR_PTR(-ENOMEM);
if (IS_ERR(rq))
return rq;
blk_rq_set_block_pc(rq);
ret = blk_fill_sgv4_hdr_rq(q, rq, hdr, bd, has_write_perm);
@ -285,8 +285,8 @@ bsg_map_hdr(struct bsg_device *bd, struct sg_io_v4 *hdr, fmode_t has_write_perm,
}
next_rq = blk_get_request(q, READ, GFP_KERNEL);
if (!next_rq) {
ret = -ENOMEM;
if (IS_ERR(next_rq)) {
ret = PTR_ERR(next_rq);
goto out;
}
rq->next_rq = next_rq;