[PATCH 4/4] fcoe: hold disc_mutex when traversing rport lists

[Hannes Reinecke <hare@xxxxxxx>]

When calling either fc_rport_logon() or fc_rport_logoff() during
rport list traversal we cannot use the RCU list traversal, as
either of these functions will be taking a mutex.
So we need to partially revert commit a407c593398c to take the
disc mutex during traversal.
We should, however, continue to use krefs to ensure that the rport
object will not be freed from under us.

Fixes: a407c593398c ("scsi: libfc: Fixup disc_mutex handling")
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
 drivers/scsi/fcoe/fcoe_ctlr.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index ea23c8dffc25..b42bfc790e04 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -2175,15 +2175,13 @@ static void fcoe_ctlr_disc_stop_locked(struct fc_lport *lport)
 {
 	struct fc_rport_priv *rdata;
 
-	rcu_read_lock();
+	mutex_lock(&lport->disc.disc_mutex);
 	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers) {
 		if (kref_get_unless_zero(&rdata->kref)) {
 			fc_rport_logoff(rdata);
 			kref_put(&rdata->kref, fc_rport_destroy);
 		}
 	}
-	rcu_read_unlock();
-	mutex_lock(&lport->disc.disc_mutex);
 	lport->disc.disc_callback = NULL;
 	mutex_unlock(&lport->disc.disc_mutex);
 }
@@ -2712,7 +2710,7 @@ static unsigned long fcoe_ctlr_vn_age(struct fcoe_ctlr *fip)
 	unsigned long deadline;
 
 	next_time = jiffies + msecs_to_jiffies(FIP_VN_BEACON_INT * 10);
-	rcu_read_lock();
+	mutex_lock(&lport->disc.disc_mutex);
 	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers) {
 		if (!kref_get_unless_zero(&rdata->kref))
 			continue;
@@ -2733,7 +2731,7 @@ static unsigned long fcoe_ctlr_vn_age(struct fcoe_ctlr *fip)
 			next_time = deadline;
 		kref_put(&rdata->kref, fc_rport_destroy);
 	}
-	rcu_read_unlock();
+	mutex_unlock(&lport->disc.disc_mutex);
 	return next_time;
 }
 
@@ -3080,8 +3078,6 @@ static void fcoe_ctlr_vn_disc(struct fcoe_ctlr *fip)
 	mutex_lock(&disc->disc_mutex);
 	callback = disc->pending ? disc->disc_callback : NULL;
 	disc->pending = 0;
-	mutex_unlock(&disc->disc_mutex);
-	rcu_read_lock();
 	list_for_each_entry_rcu(rdata, &disc->rports, peers) {
 		if (!kref_get_unless_zero(&rdata->kref))
 			continue;
@@ -3090,7 +3086,7 @@ static void fcoe_ctlr_vn_disc(struct fcoe_ctlr *fip)
 			fc_rport_login(rdata);
 		kref_put(&rdata->kref, fc_rport_destroy);
 	}
-	rcu_read_unlock();
+	mutex_unlock(&disc->disc_mutex);
 	if (callback)
 		callback(lport, DISC_EV_SUCCESS);
 }
-- 
2.12.3