[PATCH 1/3] libfc: don't schedule abort twice

[hare@kernel.org]

From: Hannes Reinecke <hare@suse.de>

The current FC error recovery is sending up to three REC (recovery)
frames in 10 second intervals, and as a final step sending an ABTS
after 30 seconds for the command itself.
Unfortunately sending an ABTS is also the action for the SCSI
abort handler, and the default timeout for scsi commands is also
30 seconds. This causes two ABTS to be scheduled, with the libfc
one slightly earlier. The ABTS scheduled by SCSI EH then sees the
command to be already aborted, and will always return with a 'GOOD'
status irrespective on the actual result from the first ABTS.
This causes the SCSI EH abort handler to always succeed, and
SCSI EH never to be engaged.
Fix this by not issuing an ABTS when a SCSI command is present
for the exchange, but rather wait for the abort scheduled from
SCSI EH.
And warn if an abort is already scheduled to avoid similar errors
in the future.

Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/libfc/fc_fcp.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/libfc/fc_fcp.c b/drivers/scsi/libfc/fc_fcp.c
index 945adca5e72f..3f189cedf6db 100644
--- a/drivers/scsi/libfc/fc_fcp.c
+++ b/drivers/scsi/libfc/fc_fcp.c
@@ -265,6 +265,11 @@ static int fc_fcp_send_abort(struct fc_fcp_pkt *fsp)
 	if (!fsp->seq_ptr)
 		return -EINVAL;
 
+	if (fsp->state & FC_SRB_ABORT_PENDING) {
+		FC_FCP_DBG(fsp, "abort already pending\n");
+		return -EBUSY;
+	}
+
 	this_cpu_inc(fsp->lp->stats->FcpPktAborts);
 
 	fsp->state |= FC_SRB_ABORT_PENDING;
@@ -1690,11 +1695,12 @@ static void fc_fcp_recovery(struct fc_fcp_pkt *fsp, u8 code)
 	fsp->status_code = code;
 	fsp->cdb_status = 0;
 	fsp->io_status = 0;
-	/*
-	 * if this fails then we let the scsi command timer fire and
-	 * scsi-ml escalate.
-	 */
-	fc_fcp_send_abort(fsp);
+	if (!fsp->cmd)
+		/*
+		 * Only abort non-scsi commands; otherwise let the
+		 * scsi command timer fire and scsi-ml escalate.
+		 */
+		fc_fcp_send_abort(fsp);
 }
 
 /**
-- 
2.35.3