From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [95.215.58.177]) (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 72E7363C for ; Mon, 22 Jan 2024 02:12:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.177 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705889544; cv=none; b=fP1SCB79dIojBivyAb9JBDdouMDaQSgMnlSuP8RuN98lGBQKlbAjnf4PaZukxMfEO/68A4vfOr1UsHFg7NrTcJBMJ2+FHlCXUy08a/RzVT5LyXZhXQwmtYC7sU/ls+AOnAbS15uHIVeeheIydv38IW4Ivc9fjldmh9hnLnAd2G0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705889544; c=relaxed/simple; bh=oNv4o9o9tRfsG+JGqIYZXTByroNF80ULNbCLqByX5AA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JDG1Vvy8Z9sz+GFC1BCemP3DuQUU+aE9KAwcews1WEWmz8BwOO1LRo+0xaYJvF8dUSZXMYQRbmK7rDBtXwoDQ1oG1EHg4wb42segsqDSug9noVp7l05UBCwnj1Edlumc0TUl8BxSNzDkG+/mZKD6tMJLeQK2BK3zoEJNWoWE7gk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=nTAto0eb; arc=none smtp.client-ip=95.215.58.177 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="nTAto0eb" Message-ID: <64270652-8e0c-4db7-b245-b970d9588918@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1705889540; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kJ9Z8zlhSyhWT9mMG7D9a1D7Qu+r3YhbOg1Qrk4gn5M=; b=nTAto0ebANGTNSyu8hi3jEJnozM3/m9YZYNi4YBF5k5jmlPPJ8CxKixhsQL8ilQ5a5imOh AMnk/pTzlmMw6jLeTaeARWDLCpeu86j3W7ZbDh3kdKRN6vdHX8v/NDkDyRBGBINo1wg+t5 H1bye+kGwTGSnCLX1OEMUnW8RuhTwZk= Date: Mon, 22 Jan 2024 10:12:15 +0800 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 1/1] virtio_net: Add timeout handler to avoid kernel hang To: Andrew Lunn , Heng Qi Cc: Paolo Abeni , Zhu Yanjun , mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org References: <20240115012918.3081203-1-yanjun.zhu@intel.com> <667a9520-a53f-40a2-810a-6c1e45146589@linux.dev> <7dd89fc0-f31e-4f83-9c02-58ee67c2d436@linux.alibaba.com> <430b899c-aed4-419d-8ae8-544bb9bec5d9@lunn.ch> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Zhu Yanjun In-Reply-To: <430b899c-aed4-419d-8ae8-544bb9bec5d9@lunn.ch> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 在 2024/1/20 1:29, Andrew Lunn 写道: >>>>>       while (!virtqueue_get_buf(vi->cvq, &tmp) && >>>>> -           !virtqueue_is_broken(vi->cvq)) >>>>> +           !virtqueue_is_broken(vi->cvq)) { >>>>> +        if (timeout) >>>>> +            timeout--; >>>> This is not really a timeout, just a loop counter. 200 iterations could >>>> be a very short time on reasonable H/W. I guess this avoid the soft >>>> lockup, but possibly (likely?) breaks the functionality when we need to >>>> loop for some non negligible time. >>>> >>>> I fear we need a more complex solution, as mentioned by Micheal in the >>>> thread you quoted. >>> Got it. I also look forward to the more complex solution to this problem. >> Can we add a device capability (new feature bit) such as ctrq_wait_timeout >> to get a reasonable timeout？ > The usual solution to this is include/linux/iopoll.h. If you can sleep > read_poll_timeout() otherwise read_poll_timeout_atomic(). I read carefully the functions read_poll_timeout() and read_poll_timeout_atomic(). The timeout is set by the caller of the 2 functions. As such, can we add a module parameter to customize this timeout value by the user? Or this timeout value is stored in device register, virtio_net driver will read this timeout value at initialization? Zhu Yanjun > > Andrew