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Message-ID: <20250827093323.432414-1-liuhangbin@gmail.com>
Date: Wed, 27 Aug 2025 09:33:23 +0000
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
MD Danish Anwar <danishanwar@...com>,
Alexander Lobakin <aleksander.lobakin@...el.com>,
Jaakko Karrenpalo <jkarrenpalo@...il.com>,
Fernando Fernandez Mancera <ffmancera@...eup.net>,
Murali Karicheri <m-karicheri2@...com>,
WingMan Kwok <w-kwok2@...com>,
Stanislav Fomichev <sdf@...ichev.me>,
Xiao Liang <shaw.leon@...il.com>,
Kuniyuki Iwashima <kuniyu@...gle.com>,
Johannes Berg <johannes.berg@...el.com>,
Hangbin Liu <liuhangbin@...il.com>
Subject: [PATCHv2 net] hsr: use proper locking when iterating over ports
hsr_for_each_port is called in many places without holding the RCU read
lock, this may trigger warnings on debug kernels like:
[ 40.457015] [ T201] WARNING: suspicious RCU usage
[ 40.457020] [ T201] 6.17.0-rc2-virtme #1 Not tainted
[ 40.457025] [ T201] -----------------------------
[ 40.457029] [ T201] net/hsr/hsr_main.c:137 RCU-list traversed in non-reader section!!
[ 40.457036] [ T201]
other info that might help us debug this:
[ 40.457040] [ T201]
rcu_scheduler_active = 2, debug_locks = 1
[ 40.457045] [ T201] 2 locks held by ip/201:
[ 40.457050] [ T201] #0: ffffffff93040a40 (&ops->srcu){.+.+}-{0:0}, at: rtnl_link_ops_get+0xf2/0x280
[ 40.457080] [ T201] #1: ffffffff92e7f968 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x5e1/0xb20
[ 40.457102] [ T201]
stack backtrace:
[ 40.457108] [ T201] CPU: 2 UID: 0 PID: 201 Comm: ip Not tainted 6.17.0-rc2-virtme #1 PREEMPT(full)
[ 40.457114] [ T201] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 40.457117] [ T201] Call Trace:
[ 40.457120] [ T201] <TASK>
[ 40.457126] [ T201] dump_stack_lvl+0x6f/0xb0
[ 40.457136] [ T201] lockdep_rcu_suspicious.cold+0x4f/0xb1
[ 40.457148] [ T201] hsr_port_get_hsr+0xfe/0x140
[ 40.457158] [ T201] hsr_add_port+0x192/0x940
[ 40.457167] [ T201] ? __pfx_hsr_add_port+0x10/0x10
[ 40.457176] [ T201] ? lockdep_init_map_type+0x5c/0x270
[ 40.457189] [ T201] hsr_dev_finalize+0x4bc/0xbf0
[ 40.457204] [ T201] hsr_newlink+0x3c3/0x8f0
[ 40.457212] [ T201] ? __pfx_hsr_newlink+0x10/0x10
[ 40.457222] [ T201] ? rtnl_create_link+0x173/0xe40
[ 40.457233] [ T201] rtnl_newlink_create+0x2cf/0x750
[ 40.457243] [ T201] ? __pfx_rtnl_newlink_create+0x10/0x10
[ 40.457247] [ T201] ? __dev_get_by_name+0x12/0x50
[ 40.457252] [ T201] ? rtnl_dev_get+0xac/0x140
[ 40.457259] [ T201] ? __pfx_rtnl_dev_get+0x10/0x10
[ 40.457285] [ T201] __rtnl_newlink+0x22c/0xa50
[ 40.457305] [ T201] rtnl_newlink+0x637/0xb20
Adding rcu_read_lock() for all hsr_for_each_port() looks confusing.
Introduce a new helper, hsr_for_each_port_rtnl(), that assumes the
RTNL lock is held. This allows callers in suitable contexts to iterate
ports safely without explicit RCU locking.
Other code paths that rely on RCU protection continue to use
hsr_for_each_port() with rcu_read_lock().
Fixes: c5a759117210 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.")
Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
---
v2: check rtnl lock for net_device_ops (Kuniyuki Iwashima)
hold rcu read lock in timer function (Kuniyuki Iwashima)
---
net/hsr/hsr_device.c | 24 ++++++++++++++----------
net/hsr/hsr_main.c | 12 ++++++++++--
net/hsr/hsr_main.h | 3 +++
net/hsr/hsr_netlink.c | 4 ----
4 files changed, 27 insertions(+), 16 deletions(-)
diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index 88657255fec1..c7d2419abecd 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -49,7 +49,7 @@ static bool hsr_check_carrier(struct hsr_port *master)
ASSERT_RTNL();
- hsr_for_each_port(master->hsr, port) {
+ hsr_for_each_port_rtnl(master->hsr, port) {
if (port->type != HSR_PT_MASTER && is_slave_up(port->dev)) {
netif_carrier_on(master->dev);
return true;
@@ -105,7 +105,7 @@ int hsr_get_max_mtu(struct hsr_priv *hsr)
struct hsr_port *port;
mtu_max = ETH_DATA_LEN;
- hsr_for_each_port(hsr, port)
+ hsr_for_each_port_rtnl(hsr, port)
if (port->type != HSR_PT_MASTER)
mtu_max = min(port->dev->mtu, mtu_max);
@@ -139,7 +139,7 @@ static int hsr_dev_open(struct net_device *dev)
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
if (port->type == HSR_PT_MASTER)
continue;
switch (port->type) {
@@ -172,7 +172,7 @@ static int hsr_dev_close(struct net_device *dev)
struct hsr_priv *hsr;
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
if (port->type == HSR_PT_MASTER)
continue;
switch (port->type) {
@@ -205,7 +205,7 @@ static netdev_features_t hsr_features_recompute(struct hsr_priv *hsr,
* may become enabled.
*/
features &= ~NETIF_F_ONE_FOR_ALL;
- hsr_for_each_port(hsr, port)
+ hsr_for_each_port_rtnl(hsr, port)
features = netdev_increment_features(features,
port->dev->features,
mask);
@@ -484,7 +484,7 @@ static void hsr_set_rx_mode(struct net_device *dev)
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
if (port->type == HSR_PT_MASTER)
continue;
switch (port->type) {
@@ -506,7 +506,7 @@ static void hsr_change_rx_flags(struct net_device *dev, int change)
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
if (port->type == HSR_PT_MASTER)
continue;
switch (port->type) {
@@ -534,7 +534,7 @@ static int hsr_ndo_vlan_rx_add_vid(struct net_device *dev,
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
if (port->type == HSR_PT_MASTER ||
port->type == HSR_PT_INTERLINK)
continue;
@@ -580,7 +580,7 @@ static int hsr_ndo_vlan_rx_kill_vid(struct net_device *dev,
hsr = netdev_priv(dev);
- hsr_for_each_port(hsr, port) {
+ hsr_for_each_port_rtnl(hsr, port) {
switch (port->type) {
case HSR_PT_SLAVE_A:
case HSR_PT_SLAVE_B:
@@ -672,9 +672,13 @@ struct net_device *hsr_get_port_ndev(struct net_device *ndev,
struct hsr_priv *hsr = netdev_priv(ndev);
struct hsr_port *port;
+ rcu_read_lock();
hsr_for_each_port(hsr, port)
- if (port->type == pt)
+ if (port->type == pt) {
+ rcu_read_unlock();
return port->dev;
+ }
+ rcu_read_unlock();
return NULL;
}
EXPORT_SYMBOL(hsr_get_port_ndev);
diff --git a/net/hsr/hsr_main.c b/net/hsr/hsr_main.c
index 192893c3f2ec..eec6e20a8494 100644
--- a/net/hsr/hsr_main.c
+++ b/net/hsr/hsr_main.c
@@ -22,9 +22,13 @@ static bool hsr_slave_empty(struct hsr_priv *hsr)
{
struct hsr_port *port;
+ rcu_read_lock();
hsr_for_each_port(hsr, port)
- if (port->type != HSR_PT_MASTER)
+ if (port->type != HSR_PT_MASTER) {
+ rcu_read_unlock();
return false;
+ }
+ rcu_read_unlock();
return true;
}
@@ -134,9 +138,13 @@ struct hsr_port *hsr_port_get_hsr(struct hsr_priv *hsr, enum hsr_port_type pt)
{
struct hsr_port *port;
+ rcu_read_lock();
hsr_for_each_port(hsr, port)
- if (port->type == pt)
+ if (port->type == pt) {
+ rcu_read_unlock();
return port;
+ }
+ rcu_read_unlock();
return NULL;
}
diff --git a/net/hsr/hsr_main.h b/net/hsr/hsr_main.h
index 135ec5fce019..33b0d2460c9b 100644
--- a/net/hsr/hsr_main.h
+++ b/net/hsr/hsr_main.h
@@ -224,6 +224,9 @@ struct hsr_priv {
#define hsr_for_each_port(hsr, port) \
list_for_each_entry_rcu((port), &(hsr)->ports, port_list)
+#define hsr_for_each_port_rtnl(hsr, port) \
+ list_for_each_entry_rcu((port), &(hsr)->ports, port_list, lockdep_rtnl_is_held())
+
struct hsr_port *hsr_port_get_hsr(struct hsr_priv *hsr, enum hsr_port_type pt);
/* Caller must ensure skb is a valid HSR frame */
diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index b120470246cc..f57c289e2322 100644
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -241,10 +241,8 @@ void hsr_nl_ringerror(struct hsr_priv *hsr, unsigned char addr[ETH_ALEN],
kfree_skb(skb);
fail:
- rcu_read_lock();
master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
netdev_warn(master->dev, "Could not send HSR ring error message\n");
- rcu_read_unlock();
}
/* This is called when we haven't heard from the node with MAC address addr for
@@ -278,10 +276,8 @@ void hsr_nl_nodedown(struct hsr_priv *hsr, unsigned char addr[ETH_ALEN])
kfree_skb(skb);
fail:
- rcu_read_lock();
master = hsr_port_get_hsr(hsr, HSR_PT_MASTER);
netdev_warn(master->dev, "Could not send HSR node down\n");
- rcu_read_unlock();
}
/* HSR_C_GET_NODE_STATUS lets userspace query the internal HSR node table
--
2.50.1
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