netdev - [PATCH net-next v2 2/9] net: stmmac: dwmac4: fix RX FIFO fill statistics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <E1vdtvi-00000002GtP-1Os1@rmk-PC.armlinux.org.uk>
Date: Thu, 08 Jan 2026 17:36:14 +0000
From: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
To: Andrew Lunn <andrew@...n.ch>,
	Heiner Kallweit <hkallweit1@...il.com>
Cc: Alexandre Torgue <alexandre.torgue@...s.st.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-stm32@...md-mailman.stormreply.com,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Maxime Coquelin <mcoquelin.stm32@...il.com>,
	netdev@...r.kernel.org,
	Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next v2 2/9] net: stmmac: dwmac4: fix RX FIFO fill
 statistics

In dwmac4_debug(), the wrong shift is used with the RXFSTS mask:

 #define MTL_DEBUG_RXFSTS_MASK          GENMASK(5, 4)
 #define MTL_DEBUG_RXFSTS_SHIFT         4
 #define MTL_DEBUG_RRCSTS_SHIFT         1

                       u32 rxfsts = (value & MTL_DEBUG_RXFSTS_MASK)
                                    >> MTL_DEBUG_RRCSTS_SHIFT;

where rxfsts is tested against small integers 1 .. 3. This results in
the tests always failing, causing the "mtl_rx_fifo__fill_level_empty"
statistic counter to always be incremented no matter what the fill
level actually is.

Fix this by using FIELD_GET() and remove the unnecessary
MTL_DEBUG_RXFSTS_SHIFT definition as FIELD_GET() will shift according
to the least siginificant set bit in the supplied field mask.

Reviewed-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac4.h      | 1 -
 drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c | 3 +--
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
index fa27639895ce..3da6891b9df7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4.h
@@ -460,7 +460,6 @@ static inline u32 mtl_low_credx_base_addr(const struct dwmac4_addrs *addrs,
 
 /* MAC debug: GMII or MII Transmit Protocol Engine Status */
 #define MTL_DEBUG_RXFSTS_MASK		GENMASK(5, 4)
-#define MTL_DEBUG_RXFSTS_SHIFT		4
 #define MTL_DEBUG_RXFSTS_EMPTY		0
 #define MTL_DEBUG_RXFSTS_BT		1
 #define MTL_DEBUG_RXFSTS_AT		2
diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
index a4282fd7c3c7..bd5f48d0b9fc 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_core.c
@@ -700,8 +700,7 @@ static void dwmac4_debug(struct stmmac_priv *priv, void __iomem *ioaddr,
 		value = readl(ioaddr + MTL_CHAN_RX_DEBUG(dwmac4_addrs, queue));
 
 		if (value & MTL_DEBUG_RXFSTS_MASK) {
-			u32 rxfsts = (value & MTL_DEBUG_RXFSTS_MASK)
-				     >> MTL_DEBUG_RRCSTS_SHIFT;
+			u32 rxfsts = FIELD_GET(MTL_DEBUG_RXFSTS_MASK, value);
 
 			if (rxfsts == MTL_DEBUG_RXFSTS_FULL)
 				x->mtl_rx_fifo_fill_level_full++;
-- 
2.47.3