From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38969) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vr6kQ-00086K-KP for qemu-devel@nongnu.org; Thu, 12 Dec 2013 08:56:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Vr6kK-0005z8-ME for qemu-devel@nongnu.org; Thu, 12 Dec 2013 08:56:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59054) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Vr6kK-0005z3-EF for qemu-devel@nongnu.org; Thu, 12 Dec 2013 08:56:08 -0500 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id rBCDu7f8016064 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Thu, 12 Dec 2013 08:56:07 -0500 From: Markus Armbruster References: <1386836626-6436-1-git-send-email-famz@redhat.com> <1386836626-6436-9-git-send-email-famz@redhat.com> Date: Thu, 12 Dec 2013 14:56:04 +0100 In-Reply-To: <1386836626-6436-9-git-send-email-famz@redhat.com> (Fam Zheng's message of "Thu, 12 Dec 2013 16:23:44 +0800") Message-ID: <87fvpy6umj.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v7 08/10] block: Add checks of blocker in block operations List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: kwolf@redhat.com, qemu-devel@nongnu.org, rjones@redhat.com, imain@redhat.com, stefanha@redhat.com, pbonzini@redhat.com Fam Zheng writes: > Before operate on a BlockDriverState, respective types are checked > against bs->op_blockers and it will error out if there's a blocker. > > Signed-off-by: Fam Zheng So this patch adds protection against "two of the same kind simultaneously". How could we check it's complete? Have we pondered the more general problem of which "operations" (whatever that is) exclude each other? [...]