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d="scan'208";a="9407797" Date: Mon, 9 Dec 2019 18:17:57 +0100 From: Roger Pau =?iso-8859-1?Q?Monn=E9?= To: "Durrant, Paul" CC: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , "Juergen Gross" , Stefano Stabellini , "Boris Ostrovsky" Subject: Re: [Xen-devel] [PATCH 2/4] xenbus: limit when state is forced to closed Message-ID: <20191209171757.GC980@Air-de-Roger> References: <20191205140123.3817-1-pdurrant@amazon.com> <20191205140123.3817-3-pdurrant@amazon.com> <20191209113926.GS980@Air-de-Roger> <19b5c2fa36b842e58bbdddd602c4e672@EX13D32EUC003.ant.amazon.com> <20191209122537.GV980@Air-de-Roger> <54e3cd3a42d8418d9a36388315deab13@EX13D32EUC003.ant.amazon.com> <20191209142852.GW980@Air-de-Roger> <20191209151339.GZ980@Air-de-Roger> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.12.2 (2019-09-21) X-ClientProxiedBy: AMSPEX02CAS01.citrite.net (10.69.22.112) To AMSPEX02CL03.citrite.net (10.69.22.127) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 09, 2019 at 04:26:15PM +0000, Durrant, Paul wrote: > > > If you want unbind to actually do a proper unplug then that's extra work > > and not really something I want to tackle (and re-bind would still need to > > be toolstack initiated as something would have to re-create the xenstore > > area). > > > > Why do you say the xenstore area would need to be recreated? > > > > Setting state to closed shouldn't cause any cleanup of the xenstore > > area, as that should already happen for example when using pvgrub > > since in that case grub itself disconnects and already causes a > > transition to closed and a re-attachment afterwards by the guest > > kernel. > > > > For some reason, when I originally tested, the xenstore area disappeared. I checked again and it did not this time. I just ended up with a frontend stuck in state 5 (because it is the system disk and won't go offline) trying to talk to a non-existent backend. Upon re-bind the backend goes into state 5 (because it sees the 5 in the frontend) and leaves the guest wedged. Likely blkfront should go back to init state, but anyway, that's not something that needs fixing as part of this series. Thanks, Roger.