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Message-ID: <20250216233245.3122700-10-sdf@fomichev.me>
Date: Sun, 16 Feb 2025 15:32:42 -0800
From: Stanislav Fomichev <sdf@...ichev.me>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com
Subject: [PATCH net-next v3 09/12] net: replace dev_addr_sem with netdev instance lock
Lockdep reports possible circular dependency in [0]. Instead of
fixing the ordering, replace global dev_addr_sem with netdev
instance lock. Most of the paths that set/get mac are RTNL
protected. Two places where it's not, convert to explicit
locking:
- sysfs address_show
- dev_get_mac_address via dev_ioctl
0: https://netdev-3.bots.linux.dev/vmksft-forwarding-dbg/results/993321/24-router-bridge-1d-lag-sh/stderr
Signed-off-by: Stanislav Fomichev <sdf@...ichev.me>
---
drivers/net/tap.c | 2 +-
drivers/net/tun.c | 2 +-
include/linux/netdevice.h | 6 +----
net/core/dev.c | 52 ++++++++++++++++++++-------------------
net/core/dev.h | 3 +--
net/core/dev_api.c | 17 ++-----------
net/core/dev_ioctl.c | 2 +-
net/core/net-sysfs.c | 7 ++----
net/core/rtnetlink.c | 6 ++++-
9 files changed, 41 insertions(+), 56 deletions(-)
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index d4ece538f1b2..4382f5e323b0 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -1017,7 +1017,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
rtnl_unlock();
return -ENOLINK;
}
- ret = dev_set_mac_address_user(tap->dev, &sa, NULL);
+ ret = dev_set_mac_address(tap->dev, &sa, NULL);
tap_put_tap_dev(tap);
rtnl_unlock();
return ret;
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index d8f4d3e996a7..1e645d5e225c 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -3175,7 +3175,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
case SIOCSIFHWADDR:
/* Set hw address */
- ret = dev_set_mac_address_user(tun->dev, &ifr.ifr_hwaddr, NULL);
+ ret = dev_set_mac_address(tun->dev, &ifr.ifr_hwaddr, NULL);
break;
case TUNGETSNDBUF:
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 53fc0d02abc8..03fd15639d94 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2463,7 +2463,7 @@ struct net_device {
*
* Protects:
* @gro_flush_timeout, @napi_defer_hard_irqs, @napi_list,
- * @net_shaper_hierarchy, @reg_state, @threaded
+ * @net_shaper_hierarchy, @reg_state, @threaded, @dev_addr
*
* Partially protects (writers must hold both @lock and rtnl_lock):
* @up
@@ -4206,10 +4206,6 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
struct netlink_ext_ack *extack);
int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
struct netlink_ext_ack *extack);
-int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
- struct netlink_ext_ack *extack);
-int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
- struct netlink_ext_ack *extack);
int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name);
int dev_get_port_parent_id(struct net_device *dev,
struct netdev_phys_item_id *ppid, bool recurse);
diff --git a/net/core/dev.c b/net/core/dev.c
index ac3713c74bcb..fa8fec1c1027 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1058,6 +1058,28 @@ struct net_device *netdev_get_by_index_lock(struct net *net, int ifindex)
return __netdev_put_lock(dev);
}
+/**
+ * netdev_get_by_name_lock() - find a device by its name
+ * @net: the applicable net namespace
+ * @name: name of device
+ *
+ * Search for an interface by name. If a valid device
+ * with @name is found it will be returned with netdev->lock held.
+ * netdev_unlock() must be called to release it.
+ *
+ * Return: pointer to a device with lock held, NULL if not found.
+ */
+struct net_device *netdev_get_by_name_lock(struct net *net, const char *name)
+{
+ struct net_device *dev;
+
+ dev = dev_get_by_name(net, name);
+ if (!dev)
+ return NULL;
+
+ return __netdev_put_lock(dev);
+}
+
struct net_device *
netdev_xa_find_lock(struct net *net, struct net_device *dev,
unsigned long *index)
@@ -9374,44 +9396,24 @@ int netif_set_mac_address(struct net_device *dev, struct sockaddr *sa,
return 0;
}
-DECLARE_RWSEM(dev_addr_sem);
-
-int netif_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
- struct netlink_ext_ack *extack)
-{
- int ret;
-
- down_write(&dev_addr_sem);
- ret = netif_set_mac_address(dev, sa, extack);
- up_write(&dev_addr_sem);
- return ret;
-}
-
int dev_get_mac_address(struct sockaddr *sa, struct net *net, char *dev_name)
{
size_t size = sizeof(sa->sa_data_min);
struct net_device *dev;
- int ret = 0;
- down_read(&dev_addr_sem);
- rcu_read_lock();
+ dev = netdev_get_by_name_lock(net, dev_name);
+ if (!dev)
+ return -ENODEV;
- dev = dev_get_by_name_rcu(net, dev_name);
- if (!dev) {
- ret = -ENODEV;
- goto unlock;
- }
if (!dev->addr_len)
memset(sa->sa_data, 0, size);
else
memcpy(sa->sa_data, dev->dev_addr,
min_t(size_t, size, dev->addr_len));
sa->sa_family = dev->type;
+ netdev_unlock(dev);
-unlock:
- rcu_read_unlock();
- up_read(&dev_addr_sem);
- return ret;
+ return 0;
}
EXPORT_SYMBOL(dev_get_mac_address);
diff --git a/net/core/dev.h b/net/core/dev.h
index 41b0831aba60..b50ca645c086 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -28,6 +28,7 @@ netdev_napi_by_id_lock(struct net *net, unsigned int napi_id);
struct net_device *dev_get_by_napi_id(unsigned int napi_id);
struct net_device *netdev_get_by_index_lock(struct net *net, int ifindex);
+struct net_device *netdev_get_by_name_lock(struct net *net, const char *name);
struct net_device *__netdev_put_lock(struct net_device *dev);
struct net_device *
netdev_xa_find_lock(struct net *net, struct net_device *dev,
@@ -69,8 +70,6 @@ extern int weight_p;
extern int dev_weight_rx_bias;
extern int dev_weight_tx_bias;
-extern struct rw_semaphore dev_addr_sem;
-
/* rtnl helpers */
extern struct list_head net_todo_list;
void netdev_run_todo(void);
diff --git a/net/core/dev_api.c b/net/core/dev_api.c
index 0db20ed086d3..68d294e6d48d 100644
--- a/net/core/dev_api.c
+++ b/net/core/dev_api.c
@@ -82,19 +82,6 @@ void dev_set_group(struct net_device *dev, int new_group)
netdev_unlock_ops(dev);
}
-int dev_set_mac_address_user(struct net_device *dev, struct sockaddr *sa,
- struct netlink_ext_ack *extack)
-{
- int ret;
-
- netdev_lock_ops(dev);
- ret = netif_set_mac_address_user(dev, sa, extack);
- netdev_unlock_ops(dev);
-
- return ret;
-}
-EXPORT_SYMBOL(dev_set_mac_address_user);
-
/**
* dev_change_net_namespace() - move device to different nethost namespace
* @dev: device
@@ -310,9 +297,9 @@ int dev_set_mac_address(struct net_device *dev, struct sockaddr *sa,
{
int ret;
- netdev_lock_ops(dev);
+ netdev_lock(dev);
ret = netif_set_mac_address(dev, sa, extack);
- netdev_unlock_ops(dev);
+ netdev_unlock(dev);
return ret;
}
diff --git a/net/core/dev_ioctl.c b/net/core/dev_ioctl.c
index d9f350593121..296e52d1395d 100644
--- a/net/core/dev_ioctl.c
+++ b/net/core/dev_ioctl.c
@@ -574,7 +574,7 @@ static int dev_ifsioc(struct net *net, struct ifreq *ifr, void __user *data,
case SIOCSIFHWADDR:
if (dev->addr_len > sizeof(struct sockaddr))
return -EINVAL;
- return dev_set_mac_address_user(dev, &ifr->ifr_hwaddr, NULL);
+ return dev_set_mac_address(dev, &ifr->ifr_hwaddr, NULL);
case SIOCSIFHWBROADCAST:
if (ifr->ifr_hwaddr.sa_family != dev->type)
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 35f79a308d7b..960c78f1fa21 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -262,14 +262,11 @@ static ssize_t address_show(struct device *dev, struct device_attribute *attr,
struct net_device *ndev = to_net_dev(dev);
ssize_t ret = -EINVAL;
- down_read(&dev_addr_sem);
-
- rcu_read_lock();
+ netdev_lock(ndev);
if (dev_isalive(ndev))
ret = sysfs_format_mac(buf, ndev->dev_addr, ndev->addr_len);
- rcu_read_unlock();
+ netdev_unlock(ndev);
- up_read(&dev_addr_sem);
return ret;
}
static DEVICE_ATTR_RO(address);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index c5e42e665f3a..8af0db79f72c 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3085,7 +3085,11 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev,
sa->sa_family = dev->type;
memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]),
dev->addr_len);
- err = netif_set_mac_address_user(dev, sa, extack);
+ if (!netdev_need_ops_lock(dev))
+ netdev_lock(dev);
+ err = netif_set_mac_address(dev, sa, extack);
+ if (!netdev_need_ops_lock(dev))
+ netdev_unlock(dev);
kfree(sa);
if (err)
goto errout;
--
2.48.1
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