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=1792510583; b=lbmGdQ88CyQLsEX4CZtBBdN0hE61+oXkmd+UrFru7TFtD73pFZmiC+KreYAkQYR38R22 WY5EAGQRxbdUaoFB167USIck2qsIEaE3YfdOQnsVdLOs0AOVwb4A/CyWX2vbRuvygJ5ix cuOx4wXO4Gdpbg/buo9MnQbDMGKdtHKe8brX51PU/LLnYBJ2qvDlNqrnpO+Evl6Y/d7IJ VJnCR/nvwky+X1uCiVM2p/gb5CiSroJJltD3tU1Ot0QWrB/CGdamdg6CV+eEh7z2xQhse zvRrr1Bq+Krvr3QoN9lPrvu8q8U8ZPQ7fTpEICxICAW1txH9aIPvU+RNayADXgtowtw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792510583; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=iisecgbWNUqKMQdJu3346ehlewHqxPUFcrMwlliEavw=; b=t6i9zPTxkxZwWMCG2dsYk+nfOtlj8YDVQ27prNmAZ04TYDFW3QcERH1T41MZd9w1Ifms GqRFnGy0qbkL49o6vxnhVJQL46pZoNtpWYr172KbZD7bZEpdLivdy7SzIuT0v05/GU626 gduT/GXOfZGPGEONM9jtp1pjDWF15ELp5HeLy2YuELR6Suk/b7tGQD38QVMmCzmMfYV+Q V15SxrSgjGwZAL2nJxGhIFosaYaG1MGc9okJzYW7bPPJNNA/XvmiC5QYt/dA5WoXbEDGG HZUv3JIT/hlM9Pqt6kA/eUGuw2adEzI10NmMV44aY1d9Q3GGabsWwCD4KVJlLGTmJNA== 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=Ahfat5c2; 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 701B2606A319 for ; Tue, 20 Oct 2026 15:36:23 +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=Ahfat5c2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE5081F000C6; Tue, 20 Oct 2026 15:36:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792510583; bh=iisecgbWNUqKMQdJu3346ehlewHqxPUFcrMwlliEavw=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=Ahfat5c2pdP9S3BqwKn60cCr6le23WAYSmb6y852qgxD9DKhj8nNda3RcwvUCnNHX XZ6fjvfJl5dXuWcJb6sK8CO9unpyaDbDm8UMwcC4Gli0sv8a14dvhfRtfo8g/EpmVM mJdXJs9yqQBEqEacDTYYlA17Xa03u/6JKwFa1FzUIf+G22JYvMf5Lu0VU6mCLRLIzp 5Kt/0fRcUmBSRs8oE1UBoM/SBgxsA5V26it6Vb8CQa7gKFmF4yHQG/rtYRk50ayElb Ds7W7cZRWoW4XuAtSiCQZ0jCBQPkkygR7FdTBTyeyq3C5DUstByZOV7ckkTwm5IfAS 2nZX6Pb7OVhbQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH net v4] usbnet: fix EVENT_RX_PAUSED race in usbnet_skb_return() Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?w5ZtZXIgTWV0ZSBLYXlh?= Cc: linux-usb@vger.kernel.org In-Reply-To: <20261020153044.18828-1-omermetekaya0@gmail.com> References: <20261020153044.18828-1-omermetekaya0@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Tue, 20 Oct 2026 15:36:13 +0000 X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > On SMP, usbnet_skb_return() can observe EVENT_RX_PAUSED as set on CPU0 > while usbnet_resume_rx() clears the flag and drains rxq_pause on CPU1. > The skb can then be queued after the drain has completed and remain > stranded until the next MTU change or device stop. >=20 > Synchronize the EVENT_RX_PAUSED state transition and paused-queue > dequeue operations with rxq_pause.lock, dropping the lock around each > usbnet_skb_return() call to avoid lock inversion. In usbnet_skb_return() > use a double-check pattern under rxq_pause.lock on the slow path, > keeping the normal RX fast path lock-free. Use spin_lock_irqsave() to > match the lockdep class shared with other sk_buff_head locks taken from > hardirq context in defer_bh(). >=20 > Discovered by Sashiko, not triggered, not runtime-tested. >=20 > Fixes: 43daa96b166c ("usbnet: Stop RX Q on MTU change") > Signed-off-by: =C3=96mer Mete Kaya Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261020153044.1882= 8-1-omermetekaya0@gmail.com?part=3D1