5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiner Kallweit <hkallweit1@xxxxxxxxx> [ Upstream commit ca1ab89cd2d654661f559bd83ad9fc7323cb6c86 ] We can simplify the for() condition and eliminate variable tx_left. The change also considers that tp->cur_tx may be incremented by a racing rtl8169_start_xmit(). In addition replace the write to tp->dirty_tx and the following smp_mb() with an equivalent call to smp_store_mb(). This implicitly adds a WRITE_ONCE() to the write. Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> Link: https://lore.kernel.org/r/c2e19e5e-3d3f-d663-af32-13c3374f5def@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Stable-dep-of: c71e3a5cffd5 ("r8169: Fix possible ring buffer corruption on fragmented Tx packets.") Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/ethernet/realtek/r8169_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c index 84c8362a65cd1..0847b64fbb2f4 100644 --- a/drivers/net/ethernet/realtek/r8169_main.c +++ b/drivers/net/ethernet/realtek/r8169_main.c @@ -4469,11 +4469,11 @@ static void rtl8169_pcierr_interrupt(struct net_device *dev) static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp, int budget) { - unsigned int dirty_tx, tx_left, bytes_compl = 0, pkts_compl = 0; + unsigned int dirty_tx, bytes_compl = 0, pkts_compl = 0; dirty_tx = tp->dirty_tx; - for (tx_left = READ_ONCE(tp->cur_tx) - dirty_tx; tx_left; tx_left--) { + while (READ_ONCE(tp->cur_tx) != dirty_tx) { unsigned int entry = dirty_tx % NUM_TX_DESC; struct sk_buff *skb = tp->tx_skb[entry].skb; u32 status; @@ -4497,7 +4497,6 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp, rtl_inc_priv_stats(&tp->tx_stats, pkts_compl, bytes_compl); - tp->dirty_tx = dirty_tx; /* Sync with rtl8169_start_xmit: * - publish dirty_tx ring index (write barrier) * - refresh cur_tx ring index and queue status (read barrier) @@ -4505,7 +4504,7 @@ static void rtl_tx(struct net_device *dev, struct rtl8169_private *tp, * a racing xmit thread can only have a right view of the * ring status. */ - smp_mb(); + smp_store_mb(tp->dirty_tx, dirty_tx); if (netif_queue_stopped(dev) && rtl_tx_slots_avail(tp, MAX_SKB_FRAGS)) { netif_wake_queue(dev); -- 2.43.0
