From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C5694C3DA7F for ; Wed, 31 Jul 2024 14:11:09 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sZA2i-0002Es-TF; Wed, 31 Jul 2024 10:11:04 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sZA2h-0002AI-Lk for qemu-devel@nongnu.org; Wed, 31 Jul 2024 10:11:03 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sZA2g-0004lM-1C for qemu-devel@nongnu.org; Wed, 31 Jul 2024 10:11:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722435059; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=BRvORSIQgukT3HX62citwsPVtIu/9z1HbQalEpRu9rA=; b=OFvAJ9z5t/GzmdgvxFjLVxJl90SmR7TLU1OS3A60CryNpCtnTDadYEV9MoSRi5ee0z/Kk/ izeA04k3m8C6gpisIW9D3cDPCy0OInr0I4GAxmw5a+9vdhIA89I/4IFhvDT8REMvi2t+bH hyNFt2k/fY24EKlmEapikoLgEd3gJZs= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-534-BCLbsNelMayWEsO_CCMZRg-1; Wed, 31 Jul 2024 10:10:57 -0400 X-MC-Unique: BCLbsNelMayWEsO_CCMZRg-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9C7DB19540F2; Wed, 31 Jul 2024 14:10:55 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.33]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D975F19560AE; Wed, 31 Jul 2024 14:10:52 +0000 (UTC) Date: Wed, 31 Jul 2024 15:10:49 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Philipp Reisner Cc: qemu-devel@nongnu.org, Fabiano Rosas , Peter Xu , Paolo Bonzini , David Hildenbrand Subject: Re: [PATCH] util: retry open() when it gets interrupted by a signal Message-ID: References: <20240731132524.308273-1-philipp.reisner@linbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240731132524.308273-1-philipp.reisner@linbit.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.126, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Jul 31, 2024 at 03:25:24PM +0200, Philipp Reisner wrote: > As with many syscalls, open() might be interrupted by a signal. > > The experienced logfile entry is: > > qemu-system-x86_64: -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=libvirt-2-format,id=virtio-disk0,bootindex=2,write-cache=on,serial=1b990c4d13b74a4e90ea: Could not open '/dev/drbd1003': Interrupted system call > > Retry it until it is not interrupted by a signal. As you say, many syscalls can be interruptted by signals, so special casing open() isn't really a solution - its just addressing one specific instance you happened to see. If there are certain signals that we don't want to have a fatal interruption for, it'd be better to set SA_RESTART with sigaction, which will auto-restart a large set of syscalls, while allowing other signals to be fatal. > FYI, dd has the same kind of loop aroud open(). > https://github.com/coreutils/coreutils/blob/1ae98dbda7322427e8226356fd110d2553f5fac9/src/dd.c#L1294-L1299 > > Signed-off-by: Philipp Reisner > --- > util/osdep.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/util/osdep.c b/util/osdep.c > index 770369831b..a1269d9345 100644 > --- a/util/osdep.c > +++ b/util/osdep.c > @@ -294,14 +294,17 @@ bool qemu_has_direct_io(void) > static int qemu_open_cloexec(const char *name, int flags, mode_t mode) > { > int ret; > + do { > #ifdef O_CLOEXEC > - ret = open(name, flags | O_CLOEXEC, mode); > + ret = open(name, flags | O_CLOEXEC, mode); > #else > - ret = open(name, flags, mode); > - if (ret >= 0) { > - qemu_set_cloexec(ret); > - } > + ret = open(name, flags, mode); > + if (ret >= 0) { > + qemu_set_cloexec(ret); > + } > #endif > + } while (ret == -1 && errno == EINTR); > + > return ret; > } > > -- > 2.45.2 > > With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|