From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-181.mta1.migadu.com (out-181.mta1.migadu.com [95.215.58.181]) (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 6A676110C for ; Sat, 20 Jan 2024 04:21:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705724477; cv=none; b=j7TEp9Nf+1g/6XeShUXs40oQOGWfDdFqxUD0fb8EOfhttfhO3iJjgOUynaQz6OqmE80NB6m0Axu8lP2qMQYOoZst6WTEKgrIJ0Upd63c+FfI0sK/Rr62SXbtowYVXR03g7PjoP5T4LtLSdtjYKId6js9ftGk7yyWHn6A762ICO4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705724477; c=relaxed/simple; bh=QyLK+OphhYc9hxQqF8HtqtQrcaiy3iMrgozIAevqjps=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=NB/yCJu/d1GdI4+SF4oDV7mKR0fiRZ3mWUpOAor0JR5GkJ/87AewqusRvG2IvM6cetz2WeB9q54bEvSj3dBYHAEalUkXPeeVo8tPAkhugaRiBiNSV69hwHVCfzlv1gZBXMV/66rcaUltYIPINJUnD4T6sfMr97Dkpm3k3myyWIQ= 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=mWtf0V/3; arc=none smtp.client-ip=95.215.58.181 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="mWtf0V/3" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1705724472; 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=BKFpauz7ZWQ55RHrqHuUkp6+YwmtIzKTQV+qqJYgyxA=; b=mWtf0V/3fwm2b1HD3lyBN1TcqPARbGV4iH0h6zhVoc/IA35kM/ZVqCLMl6fAeXnad07nE4 mI1C6GyTPUU2YJWHsVXoaLGvYAIgsHd+ECPDZTbUgW6uWyDZNtcPwoWIq2FfXJpTmrChWK NVjBU2PLJbJ24CovFYk6Tzk5aB3JXdY= Date: Sat, 20 Jan 2024 12:21:05 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org 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(). Thanks. The 2 functions read_poll_timeout() and read_poll_timeout_atomic() are interesting. Zhu Yanjun > > Andrew