libfc: Protect ep->esb_stat changes via ex_lock

This patch avoids that the WARN_ON(!(ep->esb_stat & ESB_ST_SEQ_INIT))
statement in fc_seq_send_locked() gets triggered sporadically when
running FCoE target code due to concurrent ep->esb_stat modifications.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 7000203845bd136f15d30b2069e9088b83f2181b..bc0aba4fabb4a44d47f53bb5ee4d1a23f48ccab4 100644 (file)
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -988,6 +988,7 @@ static enum fc_pf_rjt_reason fc_seq_lookup_recip(struct fc_lport *lport,
                }
        }
 
+       spin_lock_bh(&ep->ex_lock);
        /*
         * At this point, we have the exchange held.
         * Find or create the sequence.
@@ -1015,11 +1016,11 @@ static enum fc_pf_rjt_reason fc_seq_lookup_recip(struct fc_lport *lport,
                                 * sending RSP, hence write request on other
                                 * end never finishes.
                                 */
-                               spin_lock_bh(&ep->ex_lock);
                                sp->ssb_stat |= SSB_ST_RESP;
                                sp->id = fh->fh_seq_id;
-                               spin_unlock_bh(&ep->ex_lock);
                        } else {
+                               spin_unlock_bh(&ep->ex_lock);
+
                                /* sequence/exch should exist */
                                reject = FC_RJT_SEQ_ID;
                                goto rel;
@@ -1030,6 +1031,7 @@ static enum fc_pf_rjt_reason fc_seq_lookup_recip(struct fc_lport *lport,
 
        if (f_ctl & FC_FC_SEQ_INIT)
                ep->esb_stat |= ESB_ST_SEQ_INIT;
+       spin_unlock_bh(&ep->ex_lock);
 
        fr_seq(fp) = sp;
 out:
@@ -1479,8 +1481,11 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp)
 
        f_ctl = ntoh24(fh->fh_f_ctl);
        fr_seq(fp) = sp;
+
+       spin_lock_bh(&ep->ex_lock);
        if (f_ctl & FC_FC_SEQ_INIT)
                ep->esb_stat |= ESB_ST_SEQ_INIT;
+       spin_unlock_bh(&ep->ex_lock);
 
        if (fc_sof_needs_ack(sof))
                fc_seq_send_ack(sp, fp);