[SCSI] libfc: re-login to remote ports that send us LOGO

After a quick link flap, a target was seen to send us a LOGO.
Apparently, it saw an RSCN reporting that we had dropped out of the
fabric after we had logged back into it.

This is likely in larger fabrics (more than 2 FC switches) after
a quick link flap at the initiator.  Each link transition causes
an port-specific RSCN to the target.  After the link comes back up,
the initiator successfully discovers and does a PLOGI to the target
before the target sees the first RSCN reporting the initiator is gone,
and it sends a LOGO.  The target may see a subsequent RSCN saying the
port is back, but probably wouldn't send a PLOGI and leaves it
up to the initiator to re-login.

An RSCN can be delayed by the switches due to software layers but a
PLOGI is forwarded in hardware causing the PLOGI to beat the RSCN.

If a remote port is in the discovered set and sends a LOGO, re-login to it.

Signed-off-by: Joe Eykholt <jeykholt@cisco.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index 04e9846ad1b5..dc97c603744f 100644
--- a/drivers/scsi/libfc/fc_rport.c
+++ b/drivers/scsi/libfc/fc_rport.c
@@ -1340,6 +1340,8 @@ static void fc_rport_recv_logo_req(struct fc_lport *lport,
         struct fc_rport_priv *rdata;
         u32 sid;
 
+        lport->tt.seq_els_rsp_send(sp, ELS_LS_ACC, NULL);
+
         fh = fc_frame_header_get(fp);
         sid = ntoh24(fh->fh_s_id);
 
@@ -1349,13 +1351,20 @@ static void fc_rport_recv_logo_req(struct fc_lport *lport,
                 mutex_lock(&rdata->rp_mutex);
                 FC_RPORT_DBG(rdata, "Received LOGO request while in state %s\n",
                              fc_rport_state(rdata));
-                fc_rport_enter_delete(rdata, RPORT_EV_LOGO);
+
+                /*
+                 * If the remote port was created due to discovery,
+                 * log back in.  It may have seen a stale RSCN about us.
+                 */
+                if (rdata->rp_state != RPORT_ST_DELETE && rdata->disc_id)
+                        fc_rport_enter_plogi(rdata);
+                else
+                        fc_rport_enter_delete(rdata, RPORT_EV_LOGO);
                 mutex_unlock(&rdata->rp_mutex);
         } else
                 FC_RPORT_ID_DBG(lport, sid,
                                 "Received LOGO from non-logged-in port\n");
         mutex_unlock(&lport->disc.disc_mutex);
-        lport->tt.seq_els_rsp_send(sp, ELS_LS_ACC, NULL);
         fc_frame_free(fp);
 }