From: Hannes Reinecke <hare@suse.de>
Date: Wed, 11 Jul 2018 10:09:28 +0200
Subject: [PATCH] scsi: libfc: hold disc_mutex in fc_disc_stop_rports()
References: bsc#1077989
Git-commit: bc3d12b75491c0e844a8a7ce05e84de8f7d94822
Patch-mainline: v4.19-rc1

fc_disc_stop_rports() is calling fc_rport_logoff(), which in turn is
acquiring the rport mutex. So we cannot use RCU list traversal here, but
rather need to hold the disc mutex to avoid list corruption while
traversing.

Fixes: a407c593398c ("scsi: libfc: Fixup disc_mutex handling")
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 drivers/scsi/libfc/fc_disc.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/libfc/fc_disc.c b/drivers/scsi/libfc/fc_disc.c
index 50fffebaa2db..8bc81b8c34ca 100644
--- a/drivers/scsi/libfc/fc_disc.c
+++ b/drivers/scsi/libfc/fc_disc.c
@@ -62,20 +62,16 @@ static void fc_disc_restart(struct fc_disc *);
  */
 static void fc_disc_stop_rports(struct fc_disc *disc)
 {
-	struct fc_lport *lport;
 	struct fc_rport_priv *rdata;
 
-	lport = fc_disc_lport(disc);
-	lockdep_assert_held(&lport->lp_mutex);
+	lockdep_assert_held(&disc->disc_mutex);
 
-	rcu_read_lock();
-	list_for_each_entry_rcu(rdata, &disc->rports, peers) {
+	list_for_each_entry(rdata, &disc->rports, peers) {
 		if (kref_get_unless_zero(&rdata->kref)) {
 			fc_rport_logoff(rdata);
 			kref_put(&rdata->kref, fc_rport_destroy);
 		}
 	}
-	rcu_read_unlock();
 }
 
 /**
@@ -699,7 +695,9 @@ static void fc_disc_stop(struct fc_lport *lport)
 
 	if (disc->pending)
 		cancel_delayed_work_sync(&disc->disc_work);
+	mutex_lock(&disc->disc_mutex);
 	fc_disc_stop_rports(disc);
+	mutex_unlock(&disc->disc_mutex);
 }
 
 /**
-- 
2.16.4