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=1792848818; b=uJf/WdXAhlxsP5n73wlSOHD4+Frfu0qjbURsZTloaZn/ijeZnEu0smEQ/XRWSECU1/Wn yROhDJUbECTHjn7UPuFatOsa8fHpevtIXyU7p9W0KFXqScAt1Dr3JUzz7vcJcDAcKb6tN 5n9Aj0qfJ+RwMNNgN56WCDta6Dqa94Z3ps5lgxu/3gnEqfzqTBA8yANsDjFTzSplsmIWD 0HTByd3fZeI6I88khmjiu+3g1ZXHBn0J5dPq25W9oG+KKy31Y4kRZzyHthjpTG2GF0JAP sEtvTmoQbgWeLFqOunvUEFh0akbG6oH9STtDDEqn0+3JXCTwXB3iqoekBVLc9dT7nbg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792848818; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=V8iPnSTcWA7siu9rwWTfrRgYmyEWIr+jQ+sEYBs6CvU=; b=ZCnFUjN6WsBCdhOOQeSKi3XzLUVPrMgTfKuArN/DiL13u+cTa0/pRwNG4ek2vabHv0dl EG0mC1aG8+3ckIy1Qxidv2mkSYBfyvG343WR1Fjzikvk2c0GWRet3dWG7NFfrGe+w35NY RdPZ1tf2R+p2VbatYnFYS73tbYNSmlimlzsRS7gEpxrUHSMiTbLVNWd4YXRmMtC1p3ZUx GmLKcHtj7Wqjrp+HF67J/V0q7miA2EfUEhZYpa59sPYI6OT/huYJJKNtwEYbGZ6o7HP6S wx98vfrJgtVt6UqHXXpULwd2fBJDRGuDQ9UtJpr31T1Wo73Ve+7AmrQrWAm7w3HTJNQ== 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=ni3nypJm; 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 7499A606A31A for ; Sat, 24 Oct 2026 13:33:38 +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=ni3nypJm Received: by smtp.kernel.org (Postfix) with ESMTPSA id D1A581F01825; Sat, 24 Oct 2026 13:33:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792848818; bh=V8iPnSTcWA7siu9rwWTfrRgYmyEWIr+jQ+sEYBs6CvU=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=ni3nypJmgRDErvhx03loyoUaZu5Lp59xm25R07rYy+IduQPS72LvoLriHJ+xNtQVi pZqOrpQl0WlOk36U9mdVT85Y/cUDGbLj7prTHUIE63aYmov2890Ljytr2H5SbUDrrx 38CI2oWLaTmzT4LvN0nF9aIi523haL40XEf2bKeBjCO6it8/CxRX+MnTcoKljLzWjB Sfl8DGGLaGjWIvOkKOhnGKACBfTmMkAcO0JfYSM6R3laLGIt7NTKwCsykwbsW20RwN tUnhU0vpFz41pvAiOU8iUiQ4lLNd+QR776BjzD2lHVhXt8n7Y3N8lhlUoqZvHeA7xp GFe/l9S6fiNWA== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH net v3 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: <20261024-cdc-ncm-netpoll-v3-1-6284ca03f967@tipi-net.de> References: <20261024-cdc-ncm-netpoll-v3-0-6284ca03f967@tipi-net.de> <20261024-cdc-ncm-netpoll-v3-1-6284ca03f967@tipi-net.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 24 Oct 2026 13:33:37 +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 > Every caller of cdc_ncm_tx_fixup() holds the txq lock with BHs or IRQs > off, so the softirq user of ctx->mtx cannot interrupt it. Use plain > spin_lock(). >=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/ > Signed-off-by: Nicolai Buchwitz Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261024-cdc-ncm-ne= tpoll-v3-0-6284ca03f967@tipi-net.de?part=3D1