net: annotate writes on dev->mtu from ndo_change_mtu()

Simon reported that ndo_change_mtu() methods were never
updated to use WRITE_ONCE(dev->mtu, new_mtu) as hinted
in commit 501a90c94510 ("inet: protect against too small
mtu values.")

We read dev->mtu without holding RTNL in many places,
with READ_ONCE() annotations.

It is time to take care of ndo_change_mtu() methods
to use corresponding WRITE_ONCE()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Simon Horman <horms@kernel.org>
Closes: https://lore.kernel.org/netdev/20240505144608.GB67882@kernel.org/
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Acked-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20240506102812.3025432-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

6 files changed, 6 insertions, 6 deletions

diff --git a/drivers/net/ethernet/atheros/ag71xx.c b/drivers/net/ethernet/atheros/ag71xx.c
index 0f2f400b5bc4..a38be924cdaa 100644
--- a/drivers/net/ethernet/atheros/ag71xx.c
+++ b/drivers/net/ethernet/atheros/ag71xx.c
@@ -1788,7 +1788,7 @@ static int ag71xx_change_mtu(struct net_device *ndev, int new_mtu)
 {
 	struct ag71xx *ag = netdev_priv(ndev);
 
-	ndev->mtu = new_mtu;
+	WRITE_ONCE(ndev->mtu, new_mtu);
 	ag71xx_wr(ag, AG71XX_REG_MAC_MFL,
 		  ag71xx_max_frame_len(ndev->mtu));
 
diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c
index 49bb9a8f00e6..3d28654e5df7 100644
--- a/drivers/net/ethernet/atheros/alx/main.c
+++ b/drivers/net/ethernet/atheros/alx/main.c
@@ -1176,7 +1176,7 @@ static int alx_change_mtu(struct net_device *netdev, int mtu)
 	struct alx_priv *alx = netdev_priv(netdev);
 	int max_frame = ALX_MAX_FRAME_LEN(mtu);
 
-	netdev->mtu = mtu;
+	WRITE_ONCE(netdev->mtu, mtu);
 	alx->hw.mtu = mtu;
 	alx->rxbuf_size = max(max_frame, ALX_DEF_RXBUF_SIZE);
 	netdev_update_features(netdev);
diff --git a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
index 46cdc32b4e31..c571614b1d50 100644
--- a/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
+++ b/drivers/net/ethernet/atheros/atl1c/atl1c_main.c
@@ -561,7 +561,7 @@ static int atl1c_change_mtu(struct net_device *netdev, int new_mtu)
 	if (netif_running(netdev)) {
 		while (test_and_set_bit(__AT_RESETTING, &adapter->flags))
 			msleep(1);
-		netdev->mtu = new_mtu;
+		WRITE_ONCE(netdev->mtu, new_mtu);
 		adapter->hw.max_frame_size = new_mtu;
 		atl1c_set_rxbufsize(adapter, netdev);
 		atl1c_down(adapter);
diff --git a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
index 5f2a6fcba967..9b778b34b67e 100644
--- a/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
+++ b/drivers/net/ethernet/atheros/atl1e/atl1e_main.c
@@ -428,7 +428,7 @@ static int atl1e_change_mtu(struct net_device *netdev, int new_mtu)
 	if (netif_running(netdev)) {
 		while (test_and_set_bit(__AT_RESETTING, &adapter->flags))
 			msleep(1);
-		netdev->mtu = new_mtu;
+		WRITE_ONCE(netdev->mtu, new_mtu);
 		adapter->hw.max_frame_size = new_mtu;
 		adapter->hw.rx_jumbo_th = (max_frame + 7) >> 3;
 		atl1e_down(adapter);
diff --git a/drivers/net/ethernet/atheros/atlx/atl1.c b/drivers/net/ethernet/atheros/atlx/atl1.c
index a9014d7932db..3afd3627ce48 100644
--- a/drivers/net/ethernet/atheros/atlx/atl1.c
+++ b/drivers/net/ethernet/atheros/atlx/atl1.c
@@ -2687,7 +2687,7 @@ static int atl1_change_mtu(struct net_device *netdev, int new_mtu)
 	adapter->rx_buffer_len = (max_frame + 7) & ~7;
 	adapter->hw.rx_jumbo_th = adapter->rx_buffer_len / 8;
 
-	netdev->mtu = new_mtu;
+	WRITE_ONCE(netdev->mtu, new_mtu);
 	if (netif_running(netdev)) {
 		atl1_down(adapter);
 		atl1_up(adapter);
diff --git a/drivers/net/ethernet/atheros/atlx/atl2.c b/drivers/net/ethernet/atheros/atlx/atl2.c
index bcfc9488125b..fa9a4919f25d 100644
--- a/drivers/net/ethernet/atheros/atlx/atl2.c
+++ b/drivers/net/ethernet/atheros/atlx/atl2.c
@@ -905,7 +905,7 @@ static int atl2_change_mtu(struct net_device *netdev, int new_mtu)
 	struct atl2_hw *hw = &adapter->hw;
 
 	/* set MTU */
-	netdev->mtu = new_mtu;
+	WRITE_ONCE(netdev->mtu, new_mtu);
 	hw->max_frame_size = new_mtu;
 	ATL2_WRITE_REG(hw, REG_MTU, new_mtu + ETH_HLEN +
 		       VLAN_HLEN + ETH_FCS_LEN);