From: Heiner Kallweit <[email protected]>

[ Upstream commit 95f3c5458dfa5856bb110e31d156e00d894d0134 ]

tp->dirty_tx and tp->cur_tx may be changed by a racing rtl_tx() or
rtl8169_start_xmit(). Use READ_ONCE() to annotate the races and ensure
that the compiler doesn't use cached values.

Signed-off-by: Heiner Kallweit <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 drivers/net/ethernet/realtek/r8169_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c 
b/drivers/net/ethernet/realtek/r8169_main.c
index fd5adb0c54d29..fca8252b4f21d 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -5856,7 +5856,8 @@ static bool rtl8169_tso_csum_v2(struct rtl8169_private 
*tp,
 static bool rtl_tx_slots_avail(struct rtl8169_private *tp,
                               unsigned int nr_frags)
 {
-       unsigned int slots_avail = tp->dirty_tx + NUM_TX_DESC - tp->cur_tx;
+       unsigned int slots_avail = READ_ONCE(tp->dirty_tx) + NUM_TX_DESC
+                                       - READ_ONCE(tp->cur_tx);
 
        /* A skbuff with nr_frags needs nr_frags+1 entries in the tx queue */
        return slots_avail > nr_frags;
-- 
2.27.0

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