linux-kernel - [PATCH 1/2] drivers: scsi: fcoe: fcoe_ctlr: Pass lockdep expression to RCU lists

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Message-Id: <20200117153123.2648-1-frextrite@gmail.com>
Date:   Fri, 17 Jan 2020 21:01:23 +0530
From:   Amol Grover <frextrite@...il.com>
To:     Hannes Reinecke <hare@...e.de>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        Joel Fernandes <joel@...lfernandes.org>,
        Madhuparna Bhowmik <madhuparnabhowmik04@...il.com>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Amol Grover <frextrite@...il.com>
Subject: [PATCH 1/2] drivers: scsi: fcoe: fcoe_ctlr: Pass lockdep expression to RCU lists

lport->disc.rports and disc->rports are traversed using
list_for_each_entry_rcu outside an RCU read-side critical section but
under the protection of lport->disc.disc_mutex and disc->disc_mutex
respectively.

Hence, add corresponding lockdep expression to silence false-positive
lockdep warnings, and harden RCU lists.

Signed-off-by: Amol Grover <frextrite@...il.com>
---
 drivers/scsi/fcoe/fcoe_ctlr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 1791a393795d..0f59992c9cd9 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -2167,7 +2167,8 @@ static void fcoe_ctlr_disc_stop_locked(struct fc_lport *lport)
 	struct fc_rport_priv *rdata;
 
 	mutex_lock(&lport->disc.disc_mutex);
-	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers) {
+	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers,
+				lockdep_is_held(&lport->disc.disc_mutex)) {
 		if (kref_get_unless_zero(&rdata->kref)) {
 			fc_rport_logoff(rdata);
 			kref_put(&rdata->kref, fc_rport_destroy);
@@ -2703,7 +2704,8 @@ static unsigned long fcoe_ctlr_vn_age(struct fcoe_ctlr *fip)
 
 	next_time = jiffies + msecs_to_jiffies(FIP_VN_BEACON_INT * 10);
 	mutex_lock(&lport->disc.disc_mutex);
-	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers) {
+	list_for_each_entry_rcu(rdata, &lport->disc.rports, peers,
+				lockdep_is_held(&lport->disc.disc_mutex)) {
 		if (!kref_get_unless_zero(&rdata->kref))
 			continue;
 		frport = fcoe_ctlr_rport(rdata);
@@ -3061,7 +3063,8 @@ 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;
-	list_for_each_entry_rcu(rdata, &disc->rports, peers) {
+	list_for_each_entry_rcu(rdata, &disc->rports, peers,
+				lockdep_is_held(&disc->disc_mutex)) {
 		if (!kref_get_unless_zero(&rdata->kref))
 			continue;
 		frport = fcoe_ctlr_rport(rdata);
-- 
2.24.1