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From: Amol Grover <frextrite@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Jakub Kicinski <kuba@kernel.org>
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>
Subject: [PATCH net 2/2 RESEND] ipmr: Add lockdep expression to ipmr_for_each_table macro
Date: Sat,  9 May 2020 12:52:44 +0530	[thread overview]
Message-ID: <20200509072243.3141-2-frextrite@gmail.com> (raw)
In-Reply-To: <20200509072243.3141-1-frextrite@gmail.com>

ipmr_for_each_table() uses list_for_each_entry_rcu() for
traversing outside of an RCU read-side critical section but
under the protection of pernet_ops_rwsem. Hence add the
corresponding lockdep expression to silence the following
false-positive warning at boot:

[    0.645292] =============================
[    0.645294] WARNING: suspicious RCU usage
[    0.645296] 5.5.4-stable #17 Not tainted
[    0.645297] -----------------------------
[    0.645299] net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/ipv4/ipmr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 99c864eb6e34..950ffe9943da 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
 static void ipmr_expire_process(struct timer_list *t);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
-	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
-				lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net)					\
+	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list,	\
+				lockdep_rtnl_is_held() ||		\
+				lockdep_is_held(&pernet_ops_rwsem))
 
 static struct mr_table *ipmr_mr_table_iter(struct net *net,
 					   struct mr_table *mrt)
-- 
2.24.1


WARNING: multiple messages have this Message-ID (diff)
From: Amol Grover <frextrite@gmail.com>
To: "David S . Miller" <davem@davemloft.net>,
	Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
	Jakub Kicinski <kuba@kernel.org>
Cc: "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 2/2 RESEND] ipmr: Add lockdep expression to ipmr_for_each_table macro
Date: Sat,  9 May 2020 12:52:44 +0530	[thread overview]
Message-ID: <20200509072243.3141-2-frextrite@gmail.com> (raw)
In-Reply-To: <20200509072243.3141-1-frextrite@gmail.com>

ipmr_for_each_table() uses list_for_each_entry_rcu() for
traversing outside of an RCU read-side critical section but
under the protection of pernet_ops_rwsem. Hence add the
corresponding lockdep expression to silence the following
false-positive warning at boot:

[    0.645292] =============================
[    0.645294] WARNING: suspicious RCU usage
[    0.645296] 5.5.4-stable #17 Not tainted
[    0.645297] -----------------------------
[    0.645299] net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!!

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/ipv4/ipmr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index 99c864eb6e34..950ffe9943da 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -109,9 +109,10 @@ static void mroute_clean_tables(struct mr_table *mrt, int flags);
 static void ipmr_expire_process(struct timer_list *t);
 
 #ifdef CONFIG_IP_MROUTE_MULTIPLE_TABLES
-#define ipmr_for_each_table(mrt, net) \
-	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list, \
-				lockdep_rtnl_is_held())
+#define ipmr_for_each_table(mrt, net)					\
+	list_for_each_entry_rcu(mrt, &net->ipv4.mr_tables, list,	\
+				lockdep_rtnl_is_held() ||		\
+				lockdep_is_held(&pernet_ops_rwsem))
 
 static struct mr_table *ipmr_mr_table_iter(struct net *net,
 					   struct mr_table *mrt)
-- 
2.24.1

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

  reply	other threads:[~2020-05-09  7:24 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-09  7:22 [PATCH net 1/2 RESEND] ipmr: Fix RCU list debugging warning Amol Grover
2020-05-09  7:22 ` [Linux-kernel-mentees] " Amol Grover
2020-05-09  7:22 ` Amol Grover [this message]
2020-05-09  7:22   ` [Linux-kernel-mentees] [PATCH net 2/2 RESEND] ipmr: Add lockdep expression to ipmr_for_each_table macro Amol Grover
2020-05-09 21:19   ` Jakub Kicinski
2020-05-09 21:19     ` [Linux-kernel-mentees] " Jakub Kicinski
2020-05-12  5:17     ` Madhuparna Bhowmik
2020-05-12  5:17       ` [Linux-kernel-mentees] " Madhuparna Bhowmik
2020-05-12 16:32       ` Jakub Kicinski
2020-05-12 16:32         ` [Linux-kernel-mentees] " Jakub Kicinski
2020-05-13  5:34         ` Madhuparna Bhowmik
2020-05-13  5:34           ` [Linux-kernel-mentees] " Madhuparna Bhowmik
2020-05-12 17:17       ` Amol Grover
2020-05-12 17:17         ` [Linux-kernel-mentees] " Amol Grover
2020-05-12 21:59         ` Jakub Kicinski
2020-05-12 21:59           ` [Linux-kernel-mentees] " Jakub Kicinski
2020-05-13 11:54       ` Stephen Rothwell
2020-05-13 11:54         ` [Linux-kernel-mentees] " Stephen Rothwell

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