diff mbox series

[net-next,v4,09/12] net: replace dev_addr_sem with netdev instance lock

Message ID 20250218020948.160643-10-sdf@fomichev.me (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series net: Hold netdev instance lock during ndo operations | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 40 this patch: 40
netdev/build_tools success Errors and warnings before: 26 (+1) this patch: 26 (+1)
netdev/cc_maintainers warning 8 maintainers not CCed: jasowang@redhat.com atenart@kernel.org andrew+netdev@lunn.ch willemdebruijn.kernel@gmail.com jdamato@fastly.com horms@kernel.org kory.maincent@bootlin.com kuniyu@amazon.com
netdev/build_clang success Errors and warnings before: 541 this patch: 541
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 4116 this patch: 4116
netdev/checkpatch warning WARNING: Unknown link reference '0:', use 'Link:' or 'Closes:' instead
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 93 this patch: 93
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2025-02-18--12-00 (tests: 891)

Commit Message

Stanislav Fomichev Feb. 18, 2025, 2:09 a.m. UTC 
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@fomichev.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 mbox series

Patch

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 11873947527d..f3b1b6df775f 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
@@ -4223,10 +4223,6 @@  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 b5a607bbf4a8..6a8ddb06dfe9 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;