[PATCH 09/19] libfc: Protect ep->esb_stat changes via ex_lock

Robert Love
2013-10-21T18:01:17Z

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>
---
drivers/scsi/libfc/fc_exch.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index 7000203..bc0aba4 100644
--- 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);