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=1792570314; b=SaA4lPEIUx14MA418dib0XMHVzNyrkjq6IHd65yKy8UL9dEoC0Ttr8BcxuTuJiRJwOWU dTVs9YGS6YJgSkEhmZW4TMs1HL2kya2jDu2zYlEHzllWAFUAYHmJnqHOJ+CSvJ4d9mXjO bPde8JxKmw7tj70LVly/6tWflUvsPV8LqC1iLoYuCqlU4LZKUdQaN6yReMFf5nIwNBAzg B2KDPUhu7n3NwJjmg3dysN1okxCJQRF5gKEhwllyv7fE7u3jYgYQNb2WZKl+G7bX5I17r ltRENlFtbpUve4R7GFwhN4kW/AdufmHMZRzRZfWT5agdwJOcFKvxgbR0g1xgc8NziSQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792570314; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=cqGN88ZYSx+RjKyzmamolQzERQ0LDoNuYdNkMhp2fFo=; b=1Z1IXElUTfq4OWaHsg7Mt4cjw/XDlQH1kw0FilsR2sbHv71Q8OJvb05Bfs9Qg6UIMOq9 TClUUA6ZbtFTAx8QAyEoXZKzkB8467PrjEqsCle5NsN6bRES0dtej2E9ohgJR2J20xoCV wnEZ5OXgSFqXNp0Gk2l6x6n+8kMdpxYYSqGi52gmwxAuuNMtqcbpekhybtUD0dfvsmNf9 4rDrESm1Mojbfkp+tWaJ9nJ6VLVNph60k3QUvUm9SO7coe6PIZr7x8W9BuSt86X2MVFsm koBFK9Jt8G1IS/9NBAvv1+suoF/xDKLXlBAZiX1wqvjt/hdvHP428p7c0hy0XaZezKQ== 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=NwxxZogO; 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 C043D606A319 for ; Wed, 21 Oct 2026 08:11:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=NwxxZogO Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A1361F000C9; Wed, 21 Oct 2026 08:11:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792570313; bh=cqGN88ZYSx+RjKyzmamolQzERQ0LDoNuYdNkMhp2fFo=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=NwxxZogO/cP0u6ThODL7opcvvatYWLdYrHhKmcs7kACIPw0HFwIiMaiZtiwKyUFgM bNUY0AEjXos+95IoLPyVxOPGCNEcVlRx6dbdgqMw/+Kg/yGv8qWG0Ktt3QIuhNxrfg BgVDAzvG/FNXZ8UVSNKNyWsgt6oGj5R/TZoFSxcQFvQ4yqtilYeQMyI1HDDRsH9dWq iA3S7EObu1Jq8A2KuMg4Zzh4GtDIplF06zNvW49sc+1ikAurKV76x/7Kcuqbwwqx98 YYqmFVwMusujvW2pqJrW2x/WQ1fSpiq0mDt4T3vKC8ki0mBurUK2mxMsr0XpL6f/NT RzNUlWu3Ze37g== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH net v2 1/2] net: usb: cdc_ncm: don't enable BHs in tx_fixup under netpoll Reply-To: sashiko-reviews@lists.linux.dev To: "Nicolai Buchwitz" Cc: linux-usb@vger.kernel.org In-Reply-To: <20261021-cdc-ncm-netpoll-v2-1-8818965bbb69@tipi-net.de> References: <20261021-cdc-ncm-netpoll-v2-0-8818965bbb69@tipi-net.de> <20261021-cdc-ncm-netpoll-v2-1-8818965bbb69@tipi-net.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 21 Oct 2026 08:11:52 +0000 X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > netpoll holds the txq lock and calls ndo_start_xmit() with IRQs off but > BHs on. The spin_unlock_bh() in cdc_ncm_tx_fixup() then runs pending > softirqs. If one of them transmits, it spins on the txq lock that > netpoll holds. With netconsole on a cdc_ncm device this ends in a soft > or hard lockup. >=20 > Use spin_lock_irqsave(), which is safe both under netpoll and on the > normal xmit path. >=20 > Fixes: c84ff1d6dff3 ("cdc_ncm: reduce driver latency in the data path") > Reported-by: Mikkel Eskildsen > Closes: https://lore.kernel.org/netdev/PRAP189MB185019A5A8D411482BB6E0CDA= 9982@PRAP189MB1850.EURP189.PROD.OUTLOOK.COM/ > Tested-by: Mikkel Eskildsen > Signed-off-by: Nicolai Buchwitz Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261021-cdc-ncm-ne= tpoll-v2-0-8818965bbb69@tipi-net.de?part=3D1