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 <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd]
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/drivers/scsi/st.c b/drivers/scsi/st.c
index aff9689..59db5bf 100644
--- a/drivers/scsi/st.c
+++ b/drivers/scsi/st.c
@@ -490,7 +490,7 @@
req = blk_get_request(SRpnt->stp->device->request_queue, write,
GFP_KERNEL);
- if (!req)
+ if (IS_ERR(req))
return DRIVER_ERROR << 24;
blk_rq_set_block_pc(req);