From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 10CB6E20C for ; Mon, 25 Sep 2023 10:46:14 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id E72DD1C9B5 for ; Mon, 25 Sep 2023 10:46:13 +0200 (CEST) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS for ; Mon, 25 Sep 2023 10:46:13 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 1D99148D3C for ; Mon, 25 Sep 2023 10:46:13 +0200 (CEST) Message-ID: <1d6ae212-9b16-ab4d-e025-07664c35d06a@proxmox.com> Date: Mon, 25 Sep 2023 10:46:08 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.0 To: Dominik Csapak , Proxmox VE development discussion References: <20230912091617.26590-1-f.ebner@proxmox.com> <6ff59a25-0401-41c4-8352-379bc0bafeb3@proxmox.com> Content-Language: en-US From: Fiona Ebner In-Reply-To: <6ff59a25-0401-41c4-8352-379bc0bafeb3@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.657 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -1.473 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pve-devel] [PATCH qemu-server 1/3] fix #2816: restore: remove timeout when allocating disks X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 25 Sep 2023 08:46:14 -0000 Am 20.09.23 um 13:23 schrieb Dominik Csapak: > comment inline: Feel free to cut out irrelevant parts in the reply ;) > On 9/12/23 11:16, Fiona Ebner wrote: >> @@ -7483,14 +7483,11 @@ sub restore_vma_archive { >>           $devinfo->{$devname} = { size => $size, dev_id => $dev_id }; >>           } elsif ($line =~ m/^CTIME: /) { >>           # we correctly received the vma config, so we can disable >> -        # the timeout now for disk allocation (set to 10 minutes, so >> -        # that we always timeout if something goes wrong) >> -        alarm(600); >> +        # the timeout now for disk allocation I would interpret this comment about disabling of the timeout to be talking about the short 5 second timeout for reading the config. >> +        alarm($oldtimeout || 0); >> +        $oldtimeout = undef; > > > this part looks wrong to me, because AFAIU you want to disable the timeout > (by canceling the alarm), but what you do here is to set it to $oldtimeout > if that was set before? > > i guess what we want to do here is: > > ---- > alarm(0); > <... do stuff ...> > alarm($oldtimeout || 0); > $oldtimeout = undef; > ---- > > ? Hmm, I see what you mean. But I'd argue that it's unexpected to disable the outer timeout for the full duration of the allocation from a caller's perspective. sub in_a_hurry { alarm(120); # outer/old timeout restore_vma_archive(...); } With the code before the patch, it could take up to 5 + 600 + 120 seconds to hit the outer timeout, with your suggestion up to 5 + potentially unlimited + 120 seconds, with patched code up to 5 + 120 seconds. Since there currently are no callers setting an outer timeout, the patch doesn't make the situation worse. We could even make the calculation more complicated and have the timeout always be hit within 120 seconds in the example above, but not sure if worth it. AFAICS, we do similar "delay" of the outer timeout in e.g. run_with_timeout(), where it can also take up to $inner_timeout + $outer_timeout seconds to hit the outer timeout.