[PATCH] Remove two cancel_delayed_work() calls from the mid-layer

[Bart Van Assche <bvanassche@acm.org>]

scsi_put_command() is either invoked before blk_start_request() or
after block layer processing has completed.  scsi_cmnd.abort_work
is scheduled from inside the SCSI timeout handler.  The block layer
guarantees that either the regular completion handler
(softirq_done_fn()) or the timeout handler (rq_timed_out_fn()) is
invoked but not both. This means that scsi_put_command() is never
invoked while abort_work is scheduled.  Hence remove the
cancel_delayed_work() call from scsi_put_command().

Similarly, scsi_abort_command() is only invoked from the SCSI
timeout handler. If scsi_abort_command() is invoked for a SCSI
command with the SCSI_EH_ABORT_SCHEDULED flag set this means that
scmd_eh_abort_handler() has already invoked scsi_queue_insert() and
hence that scsi_cmnd.abort_work is no longer pending. Hence also
remove the cancel_delayed_work() call from scsi_abort_command().

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Joe Lawrence <jdl1291@gmail.com>
---
 drivers/scsi/scsi.c       | 2 +-
 drivers/scsi/scsi_error.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index 88d46fe..53b8b94 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -334,7 +334,7 @@ void scsi_put_command(struct scsi_cmnd *cmd)
 	list_del_init(&cmd->list);
 	spin_unlock_irqrestore(&cmd->device->list_lock, flags);
 
-	cancel_delayed_work(&cmd->abort_work);
+	BUG_ON(delayed_work_pending(&cmd->abort_work));
 
 	__scsi_put_command(cmd->device->host, cmd);
 }
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index f17aa7a..919ade2 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -193,7 +193,7 @@ scsi_abort_command(struct scsi_cmnd *scmd)
 		SCSI_LOG_ERROR_RECOVERY(3,
 			scmd_printk(KERN_INFO, scmd,
 				    "scmd %p previous abort failed\n", scmd));
-		cancel_delayed_work(&scmd->abort_work);
+		BUG_ON(delayed_work_pending(&scmd->abort_work));
 		return FAILED;
 	}
 
-- 
1.8.4.5