[SCSI] libfc: fix: rport_recv_req needs disc_mutex when calling rport_lookup

The rport_lookup function must be called while holding the disc_mutex.
Otherwise, the rdata could be deleted just after that by another thread.

All callers now check the state after grabbing the rdata rp_mutex.
Even though rport_lookup skips ports in DELETE state, it does that
without holding the rdata rp_mutex, so that the state may change.
Signed-off-by: NJoe Eykholt <jeykholt@cisco.com>
Signed-off-by: NRobert Love <robert.w.love@intel.com>
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

drivers/scsi/libfc/fc_rport.c

@@ -932,14 +932,17 @@ void fc_rport_recv_req(struct fc_seq *sp, struct fc_frame *fp,
 	fh = fc_frame_header_get(fp);
 	s_id = ntoh24(fh->fh_s_id);
 
+	mutex_lock(&lport->disc.disc_mutex);
 	rdata = lport->tt.rport_lookup(lport, s_id);
 	if (!rdata) {
+		mutex_unlock(&lport->disc.disc_mutex);
 		els_data.reason = ELS_RJT_UNAB;
 		lport->tt.seq_els_rsp_send(sp, ELS_LS_RJT, &els_data);
 		fc_frame_free(fp);
 		return;
 	}
 	mutex_lock(&rdata->rp_mutex);
+	mutex_unlock(&lport->disc.disc_mutex);
 
 	op = fc_frame_payload_op(fp);
 	switch (op) {