From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53588) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1djnLu-0000ej-4I for qemu-devel@nongnu.org; Mon, 21 Aug 2017 10:06:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1djnLp-00009Z-E8 for qemu-devel@nongnu.org; Mon, 21 Aug 2017 10:06:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40848) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1djnLp-00009Q-8K for qemu-devel@nongnu.org; Mon, 21 Aug 2017 10:06:45 -0400 Date: Mon, 21 Aug 2017 15:06:35 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20170821140635.GF2231@work-vm> References: <1503301464-27886-1-git-send-email-peterx@redhat.com> <20170821085851.GA4371@lemon> <20170821100555.GC30356@pxdev.xzpeter.org> <20170821101727.GB2231@work-vm> <20170821140444.GD4371@lemon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170821140444.GD4371@lemon> Subject: Re: [Qemu-devel] [RFC 0/6] monitor: allow per-monitor thread List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: Peter Xu , qemu-devel@nongnu.org, Laurent Vivier , Juan Quintela , mdroth@linux.vnet.ibm.com, Markus Armbruster , Paolo Bonzini * Fam Zheng (famz@redhat.com) wrote: > On Mon, 08/21 11:17, Dr. David Alan Gilbert wrote: > > From previous discussions we've had, one suggestion was to have some > > type of 'safe' command; once issued in a thread, the monitor thread > > would only allow other lock-free commands to be issued; it stops any > > accidents of them issuing unsafe commands. > > I'm not sure I understand. If the 'safe' command is not issued, users are > allowed to do unsafe things? What are the possible consequences of those > 'unsafe' commands? Errors/hangs/crashes? With or without the safe command no command could cause a crash. However, a command might try and take the bql and block waiting for it. With the 'safe' command only those commands that were declared as not-wanting the lock would be allowed. Dave > Fam -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK