From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794717522; b=wCdwBYyALiAJIbCQ7V7lydoT0+gDe7/ZAd6P2SwoJ9bjmtlwFO8uH8oAnZ1r0o5sYDxh RdwElPvKTZhxx7XGH2emat5WnRCkINvbzs0PjC3hfb+WAyUMCzBin9zjtW7WzIv3bLruN sEwrfQtS0a7BmK1kBe84uzJGqlA/W84pRcC8up/nbPayRGVyDF51CvY3xq+ryK5Lb2nfd BS90A74iVmucqgmlEWDogjf7hE2AYOPKZASuGx5mPzex+Okvu4ms3Qcw2Zpxvi9BgcTfC fWiT1HryryB+teQEII+rxPhGyIPtMEEOcZyyhsKJLCDLPjBuGHGihlri4C33dPHzKfQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794717522; h=Received:DKIM-Signature:From:Date:Subject:MIME-Version:Content-Type: Content-Transfer-Encoding:Message-Id:X-B4-Tracking:X-Change-ID:To:Cc: X-Mailer:X-Developer-Signature:X-Developer-Key; bh=3sk+H4+98RAl4s00138LkHpzbHdfMDnYcTQX4GZfKCE=; b=dbxlxgPr2x22XrKEzBF8FvjTOX0J/V2E50vjzmkaZmnI/dTh1nycGKs+vqqagQtvdAoR og6DHmC/J57GLCaP+kj+dDunJjbSUPLLyZr7i9KbdE8KHeD4822b441hbWW7UStQgllfy mCQykuYh0mfN/7sMuyL9PXOujb3vxX0D0g5JKxww0M7qBaD1Y4yrklGpAw6aKfJ9meNQ4 Ank0NPCQuo8RjSsgEBGxH7krlZlPe+bbQqMl3+kCCViK7DESjj5WefEv0eb8p66bE28if la9Hy1dr0kXRsDEDfQSCgECpyJ5LCtQdgUF+qfxOJvH/mUxUDCfvEIevUBM1aGusc1g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="eV/QTTAQ"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 814C5606A323; Sun, 15 Nov 2026 04:38:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=eV/QTTAQ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4229A1F000C4; Sun, 15 Nov 2026 04:38:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794717522; bh=3sk+H4+98RAl4s00138LkHpzbHdfMDnYcTQX4GZfKCE=; h=From:Date:Subject:To:Cc; b=eV/QTTAQjx8EsTQUVFKoeBT8/EcVF7mGyI6K73GhSMwvp7ErveBqwr0GVS9IEOZjl VPv3hT1TuavJfOKbhRI6cS5BfWer+030kEIgiTnh69D7pjOv+c/LRHG1TRQND48Art W+rzqUD1rdonFB189H0asId8bxnl1eRMOUAJkTgEtAC+la1iZO/0AL4AifbQevfUaS 5VTbSTmGZkha93k59EtPqoTGoKOmcnnWvS8fEuGomaQXdafFAx3zqQewRc1DgUOmSE 8F/ojkZvx8x66ugyFMvu8DgL6aJoMBZ0SDJ1oLwNchpl4LcE87s48JRjSKq3/DwdIG P3IuT2aW9JLuQ== From: Nathan Chancellor Date: Sat, 14 Nov 2026 21:38:26 -0700 Subject: [PATCH net] net: microchip: encx24j600: Avoid unsequenced accesses to jiffies in encx24j600_tx() X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261114-encx24j600-wunsequenced-v1-1-c978fc36cacd@kernel.org> X-B4-Tracking: v=1; b=H4sIAAAAAAAA/yWMMQ7CMAwAv1J5JlKcRhn4CmKgjinuYCBuSqWqf yfQ8U6628C4CBucuw0KL2Ly1AZ46oAeNx3ZSW4MwYeEiNGx0hrilLx3n6rG79oMZ5eRYk/UJwo DtPpV+C7r/3wB5Rmuh7Q6TEzz7wn7/gWZX2nVgAAAAA== X-Change-ID: 20261114-encx24j600-wunsequenced-d1c43cc36c2b To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, stable@vger.kernel.org, Nathan Chancellor X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2213; i=nathan@kernel.org; h=from:subject:message-id; bh=xxcRp0UP7mcYpCcgqOp/Ic2NGshPPqhLsHzrb0KeC2A=; b=owGbwMvMwCUmm602sfCA1DTG02pJDFk/zX34Nni/vW121+dlpM8dAROXjzWfHrhPvSfqe5lhd ThD6OV/HaUsDGJcDLJiiizVj1WPGxrOOct449QkmDmsTCBDGLg4BWAil+Yz/I/5qLePcfm2osOx 3Yu/JH0MUvQrWab2P+TB+UwrHa7bia4M/6Pdohi0l+1bfuF3+tsi+1tfX2Qxb5Jw/fZaa8NCY5F mNmYA X-Developer-Key: i=nathan@kernel.org; a=openpgp; fpr=2437CB76E544CB6AB3D9DFD399739260CB6CB716 After a recent improvement in clang to warn on unsequenced accesses to volatile variables [1], an instance appears in encx24j600_tx(), which can break the build with CONFIG_WERROR=y / W=e: drivers/net/ethernet/microchip/encx24j600.c:898:14: error: unsequenced accesses to volatile qualified 'jiffies' [-Werror,-Wunsequenced] 898 | jiffies, jiffies - dev_trans_start(dev)); | ~~~~~~~ ^ Per C11 5.1.2.3.2, accessing a volatile object is a side effect. Per C11 6.5.2, unsequenced side effects on the same scalar object are undefined behavior. Per C11 6.5.2.2.10/12, the evaluation of arguments in a function call is indeterminately sequenced, meaning any side effects in the arguments are unsequenced. Add a local variable to hold the value of jiffies before the function call so that there are no unsequenced side effects, clearing up the warning. Cc: stable@vger.kernel.org Fixes: 04fbfce7a222 ("net: Microchip encx24j600 driver") Closes: https://github.com/ClangBuiltLinux/linux/issues/2196 Link: https://github.com/llvm/llvm-project/commit/955715460eaf9188c241c74750637fc82dfcc423 [1] Signed-off-by: Nathan Chancellor --- drivers/net/ethernet/microchip/encx24j600.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/microchip/encx24j600.c b/drivers/net/ethernet/microchip/encx24j600.c index b011bf5c2305..ebc067cb2c9d 100644 --- a/drivers/net/ethernet/microchip/encx24j600.c +++ b/drivers/net/ethernet/microchip/encx24j600.c @@ -893,9 +893,10 @@ static netdev_tx_t encx24j600_tx(struct sk_buff *skb, struct net_device *dev) static void encx24j600_tx_timeout(struct net_device *dev, unsigned int txqueue) { struct encx24j600_priv *priv = netdev_priv(dev); + unsigned long j = jiffies; netif_err(priv, tx_err, dev, "TX timeout at %ld, latency %ld\n", - jiffies, jiffies - dev_trans_start(dev)); + j, j - dev_trans_start(dev)); dev->stats.tx_errors++; netif_wake_queue(dev); --- base-commit: aa40afa831ebfe45e40a23721711059f2ac584d4 change-id: 20261114-encx24j600-wunsequenced-d1c43cc36c2b Best regards, -- Cheers, Nathan