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From: Amol Grover <frextrite@gmail.com>
To: Eric Dumazet <edumazet@google.com>,
	"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] tcp: Pass lockdep expression to RCU lists
Date: Wed, 19 Feb 2020 15:35:46 +0530	[thread overview]
Message-ID: <20200219100545.27397-1-frextrite@gmail.com> (raw)

tcp_cong_list is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of tcp_cong_list_lock.

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

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/ipv4/tcp_cong.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 3737ec096650..8d4446ed309e 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -25,7 +25,8 @@ static struct tcp_congestion_ops *tcp_ca_find(const char *name)
 {
 	struct tcp_congestion_ops *e;
 
-	list_for_each_entry_rcu(e, &tcp_cong_list, list) {
+	list_for_each_entry_rcu(e, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock)) {
 		if (strcmp(e->name, name) == 0)
 			return e;
 	}
@@ -55,7 +56,8 @@ struct tcp_congestion_ops *tcp_ca_find_key(u32 key)
 {
 	struct tcp_congestion_ops *e;
 
-	list_for_each_entry_rcu(e, &tcp_cong_list, list) {
+	list_for_each_entry_rcu(e, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock)) {
 		if (e->key == key)
 			return e;
 	}
@@ -317,7 +319,8 @@ int tcp_set_allowed_congestion_control(char *val)
 	}
 
 	/* pass 2 clear old values */
-	list_for_each_entry_rcu(ca, &tcp_cong_list, list)
+	list_for_each_entry_rcu(ca, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock))
 		ca->flags &= ~TCP_CONG_NON_RESTRICTED;
 
 	/* pass 3 mark as allowed */
-- 
2.24.1

_______________________________________________
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: Eric Dumazet <edumazet@google.com>,
	"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: 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>,
	netdev@vger.kernel.org, Amol Grover <frextrite@gmail.com>
Subject: [PATCH] tcp: Pass lockdep expression to RCU lists
Date: Wed, 19 Feb 2020 15:35:46 +0530	[thread overview]
Message-ID: <20200219100545.27397-1-frextrite@gmail.com> (raw)

tcp_cong_list is traversed using list_for_each_entry_rcu
outside an RCU read-side critical section but under the protection
of tcp_cong_list_lock.

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

Signed-off-by: Amol Grover <frextrite@gmail.com>
---
 net/ipv4/tcp_cong.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 3737ec096650..8d4446ed309e 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -25,7 +25,8 @@ static struct tcp_congestion_ops *tcp_ca_find(const char *name)
 {
 	struct tcp_congestion_ops *e;
 
-	list_for_each_entry_rcu(e, &tcp_cong_list, list) {
+	list_for_each_entry_rcu(e, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock)) {
 		if (strcmp(e->name, name) == 0)
 			return e;
 	}
@@ -55,7 +56,8 @@ struct tcp_congestion_ops *tcp_ca_find_key(u32 key)
 {
 	struct tcp_congestion_ops *e;
 
-	list_for_each_entry_rcu(e, &tcp_cong_list, list) {
+	list_for_each_entry_rcu(e, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock)) {
 		if (e->key == key)
 			return e;
 	}
@@ -317,7 +319,8 @@ int tcp_set_allowed_congestion_control(char *val)
 	}
 
 	/* pass 2 clear old values */
-	list_for_each_entry_rcu(ca, &tcp_cong_list, list)
+	list_for_each_entry_rcu(ca, &tcp_cong_list, list,
+				lockdep_is_held(&tcp_cong_list_lock))
 		ca->flags &= ~TCP_CONG_NON_RESTRICTED;
 
 	/* pass 3 mark as allowed */
-- 
2.24.1


             reply	other threads:[~2020-02-19 10:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-19 10:05 Amol Grover [this message]
2020-02-19 10:05 ` [PATCH] tcp: Pass lockdep expression to RCU lists Amol Grover
2020-02-19 19:35 ` [Linux-kernel-mentees] " Eric Dumazet
2020-02-19 19:35   ` Eric Dumazet
2020-02-20  3:47   ` [Linux-kernel-mentees] " Amol Grover
2020-02-20  3:47     ` Amol Grover

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