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From: Amol Grover <frextrite@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Richard Fontana <rfontana@redhat.com>,
	Allison Randal <allison@lohutok.net>,
	Paolo Abeni <pabeni@redhat.com>
Cc: kernel test robot <lkp@intel.com>,
	"Paul E . Mckenney" <paulmck@kernel.org>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: [Linux-kernel-mentees] [PATCH] net: caif: Add lockdep expression to RCU traversal primitive
Date: Thu, 12 Mar 2020 11:04:20 +0530	[thread overview]
Message-ID: <20200312053419.12258-1-frextrite@gmail.com> (raw)

caifdevs->list is traversed using list_for_each_entry_rcu()
outside an RCU read-side critical section but under the
protection of rtnl_mutex. Hence, add the corresponding lockdep
expression to silence the following false-positive warning:

[   10.868467] =============================
[   10.869082] WARNING: suspicious RCU usage
[   10.869817] 5.6.0-rc1-00177-g06ec0a154aae4 #1 Not tainted
[   10.870804] -----------------------------
[   10.871557] net/caif/caif_dev.c:115 RCU-list traversed in non-reader section!!

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/caif/caif_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 03c7cdd8e4cb..195d2d67be8a 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c
@@ -112,7 +112,8 @@ static struct caif_device_entry *caif_get(struct net_device *dev)
 	    caif_device_list(dev_net(dev));
 	struct caif_device_entry *caifd;
 
-	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
+	list_for_each_entry_rcu(caifd, &caifdevs->list, list,
+				lockdep_rtnl_is_held()) {
 		if (caifd->netdev == dev)
 			return caifd;
 	}
-- 
2.25.1

_______________________________________________
Linux-kernel-mentees mailing list
Linux-kernel-mentees@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees

WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Richard Fontana <rfontana@redhat.com>,
	Allison Randal <allison@lohutok.net>,
	Paolo Abeni <pabeni@redhat.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org,
	Joel Fernandes <joel@joelfernandes.org>,
	Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>,
	"Paul E . Mckenney" <paulmck@kernel.org>,
	Amol Grover <frextrite@gmail.com>,
	kernel test robot <lkp@intel.com>
Subject: [PATCH] net: caif: Add lockdep expression to RCU traversal primitive
Date: Thu, 12 Mar 2020 11:04:20 +0530	[thread overview]
Message-ID: <20200312053419.12258-1-frextrite@gmail.com> (raw)

caifdevs->list is traversed using list_for_each_entry_rcu()
outside an RCU read-side critical section but under the
protection of rtnl_mutex. Hence, add the corresponding lockdep
expression to silence the following false-positive warning:

[   10.868467] =============================
[   10.869082] WARNING: suspicious RCU usage
[   10.869817] 5.6.0-rc1-00177-g06ec0a154aae4 #1 Not tainted
[   10.870804] -----------------------------
[   10.871557] net/caif/caif_dev.c:115 RCU-list traversed in non-reader section!!

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/caif/caif_dev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/caif/caif_dev.c b/net/caif/caif_dev.c
index 03c7cdd8e4cb..195d2d67be8a 100644
--- a/net/caif/caif_dev.c
+++ b/net/caif/caif_dev.c
@@ -112,7 +112,8 @@ static struct caif_device_entry *caif_get(struct net_device *dev)
 	    caif_device_list(dev_net(dev));
 	struct caif_device_entry *caifd;
 
-	list_for_each_entry_rcu(caifd, &caifdevs->list, list) {
+	list_for_each_entry_rcu(caifd, &caifdevs->list, list,
+				lockdep_rtnl_is_held()) {
 		if (caifd->netdev == dev)
 			return caifd;
 	}
-- 
2.25.1


             reply	other threads:[~2020-03-12  5:35 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12  5:34 Amol Grover [this message]
2020-03-12  5:34 ` [PATCH] net: caif: Add lockdep expression to RCU traversal primitive Amol Grover
2020-03-12  5:55 ` [Linux-kernel-mentees] " David Miller
2020-03-12  5:55   ` David Miller

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