[PATCH 58/64] libfc: re-login to remote ports that send us LOGO

Robert Love
2009-08-25T21:03:34Z

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>
---

drivers/scsi/libfc/fc_rport.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libfc/fc_rport.c b/drivers/scsi/libfc/fc_rport.c
index 04e9846..dc97c60 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);
}