From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B9BCF236A73; Fri, 9 Jan 2026 03:57:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767931072; cv=none; b=a2unCqcdaiZDRTfrdvdOKxwmMMlmGdJJDwpinhHmw+Mv3r4GL4g7B4v2Nfx+Dfvk1jUOuaLPMqLir/P8+FOPjL4C0USJST4qp1MmqJxWZJucylbWch845P9gZAR9u/vR3m0akmAaghUSpFSSuKwISVN/Q43OiBR13aPWmxIJwKw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767931072; c=relaxed/simple; bh=Nmf9zXoeCyIwIw5E73xyMm2SNdNXQJ01rBTJXi0wHbg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rNWFXhZjCTwVNemFXPF++ZX5pCor+J9+BREr/rYynqyyb9tVAgZewW96AQiat458xtGYbsx2vrGaeXGHsImFk8rf0l2U19mYIqWNTnSr2jPNOZnzpnDbGc5VCjYKEoDztO0u4ytP6O3L81xoiAkINpuLo2AaBzI3dr9JtwG+HHM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U3mLF+y4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U3mLF+y4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1A1AC4CEF1; Fri, 9 Jan 2026 03:57:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767931072; bh=Nmf9zXoeCyIwIw5E73xyMm2SNdNXQJ01rBTJXi0wHbg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U3mLF+y44uvtzoVTKnGRFO3aCo3tZ82awwOCz37kI9P4I8IkrHSqK8/ONYQsL6fmA 0M1WGN1DhsFkA3Z8hdOgANmBjriDubNEOag37b/aEtnIoMUcfbZJdpy4bKdfjihGsj B1ul2edYgVIujAVXnugRyScw4GbH5GTzu7Lz9kfllvqwKtG76Z/6WcnX8+sNFS+RuE lM5AuGXTIyagC59bD5I5Evmtnnp6lbD3zJKAFlScO6y3XHwd3ZBvi8cqIMLBDZCTB5 MXxtQez2rYKkBjNSOVnbZYQFqMIg8z+WO5CqIEcds1wzxVu8y01cx42//3QOJtHjl1 RfMNGCVqIEQTA== From: Jakub Kicinski To: mmyangfl@gmail.com Cc: Jakub Kicinski , andrew@lunn.ch, davem@davemloft.net, linux-kernel@vger.kernel.org, edumazet@google.com, olteanv@gmail.com, david.laight.linux@gmail.com, netdev@vger.kernel.org, pabeni@redhat.com, dan.carpenter@linaro.org Subject: Re: [net-next,v4,1/2] net: dsa: yt921x: Fix MIB overflow wraparound routine Date: Thu, 8 Jan 2026 19:56:43 -0800 Message-ID: <20260109035643.2902417-1-kuba@kernel.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260108004309.4087448-2-mmyangfl@gmail.com> References: <20260108004309.4087448-2-mmyangfl@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This is an AI-generated review of your patch. For local reproduction steps see https://netdev-ai.bots.linux.dev/ai-local.html --- net: dsa: yt921x: Use u64_stats_t for MIB stats This patch converts MIB statistics from plain u64 to u64_stats_t and adds u64_stats_sync protection for atomic statistics access on 32-bit systems. > diff --git a/drivers/net/dsa/yt921x.c b/drivers/net/dsa/yt921x.c > index 7b8c1549a0fb..3d87944830f6 100644 [ ... ] > @@ -762,22 +779,27 @@ yt921x_dsa_get_ethtool_stats(struct dsa_switch *ds, int port, uint64_t *data) > struct yt921x_priv *priv = to_yt921x_priv(ds); > struct yt921x_port *pp = &priv->ports[port]; > struct yt921x_mib *mib = &pp->mib; > + unsigned int start; > size_t j; > > mutex_lock(&priv->reg_lock); > yt921x_read_mib(priv, port); > mutex_unlock(&priv->reg_lock); > > - j = 0; > - for (size_t i = 0; i < ARRAY_SIZE(yt921x_mib_descs); i++) { > - const struct yt921x_mib_desc *desc = &yt921x_mib_descs[i]; > + do { > + start = u64_stats_fetch_begin(&pp->syncp); This uses pp->syncp via u64_stats_fetch_begin(), but the syncp field does not appear to be initialized with u64_stats_init() anywhere. Looking at yt921x_mdio_probe(), the port initialization loop initializes pp->index and pp->mib_read but not pp->syncp: for (size_t i = 0; i < ARRAY_SIZE(priv->ports); i++) { struct yt921x_port *pp = &priv->ports[i]; pp->index = i; INIT_DELAYED_WORK(&pp->mib_read, yt921x_poll_mib); } On 32-bit systems, u64_stats_init() calls seqcount_init() which sets up the lockdep class. Without this initialization, CONFIG_DEBUG_LOCK_ALLOC builds may produce lockdep warnings. For comparison, the xrs700x driver at drivers/net/dsa/xrs700x/xrs700x.c initializes its syncp field with u64_stats_init(&p->syncp). Should u64_stats_init(&pp->syncp) be added to the port initialization loop in yt921x_mdio_probe()? [ ... ] > diff --git a/drivers/net/dsa/yt921x.h b/drivers/net/dsa/yt921x.h > index 61bb0ab3b09a..17fee83952c2 100644 > --- a/drivers/net/dsa/yt921x.h > +++ b/drivers/net/dsa/yt921x.h [ ... ] > @@ -533,9 +535,13 @@ struct yt921x_port { > bool isolated; > > struct delayed_work mib_read; > + struct u64_stats_sync syncp; > struct yt921x_mib mib; > - u64 rx_frames; > - u64 tx_frames; > + u64_stats_t rx_frames; > + u64_stats_t tx_frames; > + > + /* only used by read routine to avoid huge allocations on the stack */ > + struct yt921x_mib mib_new; > }; -- pw-bot: cr