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bh=PbjqjmNOB56VRU1HcMxspHela8roPJnM61v+5mh1Otw=; b=aLLht1erUMDQJWqob8c+FJCSXIvk7/7VNSu3DZRBoO1+iCVSfxJye+8cK9I/6XTfkbZpV5 7HmM6UN401yBZ23ROeH0lixheW921YW3Rtktik17sTnvafs2VV1k3e0AjxLkmdVLxv+t9Q JqqvcSBdjI/VeDaTi0ALjSyVAfUiXq4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-540-FvqkQpjXPMyrigA5b15YOw-1; Thu, 21 Jan 2021 11:07:42 -0500 X-MC-Unique: FvqkQpjXPMyrigA5b15YOw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2C24A192CC44 for ; Thu, 21 Jan 2021 16:07:41 +0000 (UTC) Received: from redhat.com (ovpn-115-126.ams2.redhat.com [10.36.115.126]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 849D62DACE; Thu, 21 Jan 2021 16:07:36 +0000 (UTC) Date: Thu, 21 Jan 2021 16:07:33 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Subject: Re: Thread safety of coroutine-sigaltstack Message-ID: <20210121160733.GP3125227@redhat.com> References: <7b8155ad-0942-dc1c-f43c-bb5eb518a278@redhat.com> <445268c9-d91f-af5a-3d7e-f4c6f014ca52@redhat.com> <62d5d33c-fe2a-228b-146d-632c84d09fd5@redhat.com> <30457fa0-6d7c-4e81-2623-8551d8bf2674@redhat.com> MIME-Version: 1.0 In-Reply-To: <30457fa0-6d7c-4e81-2623-8551d8bf2674@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.168, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Kevin Wolf , Laszlo Ersek , "qemu-devel@nongnu.org" , Stefan Hajnoczi , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jan 21, 2021 at 04:14:21PM +0100, Paolo Bonzini wrote: > On 21/01/21 10:27, Max Reitz wrote: > > > > Sure, I can do that. > > > > I agree that there probably are better solutions than to wrap everything > > in a lock.  OTOH, it looks to me like this lock is the most simple > > solution.  If Daniel is right[1] and we should drop > > coroutine-sigaltstack altogether (at some point...), perhaps it is best > > to go for the most simple solution now. > > > > [1] > > https://lists.nongnu.org/archive/html/qemu-block/2021-01/msg00808.html > > Yes, between coroutine-ucontext and the upcoming coroutine-asm[1] (which I > have shelved because it was mostly a requirement for x86 CET; but it will > come back some day), sooner or later there will be no reason to keep > coroutine-sigaltstack. Porting coroutine-asm to a new architecture is easy, > I even managed to do it for s390. ;) FWIW The libucontext impl is all ASM based and has coverage for all the arches we care about: https://github.com/kaniini/libucontext so doesn't seem like there's a need for coroutine-asm if we can rely on libucontext for portability where neede. 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 :|