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From: Heiner Kallweit <hkallweit1@gmail.com>
To: Jakub Kicinski <kuba@kernel.org>,
	David Miller <davem@davemloft.net>,
	Realtek linux nic maintainers <nic_swsd@realtek.com>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: [PATCH net-next] r8169: use READ_ONCE in rtl_tx_slots_avail
Date: Wed, 11 Nov 2020 22:14:27 +0100	[thread overview]
Message-ID: <5676fee3-f6b4-84f2-eba5-c64949a371ad@gmail.com> (raw)

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 <hkallweit1@gmail.com>
---
 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 aa6f8b16d..641c94a46 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -4144,7 +4144,8 @@ 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;
-- 
2.29.2


             reply	other threads:[~2020-11-11 21:56 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-11 21:14 Heiner Kallweit [this message]
2020-11-14  0:40 ` [PATCH net-next] r8169: use READ_ONCE in rtl_tx_slots_avail patchwork-bot+netdevbpf

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