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Fri, 19 Jun 2020 16:54:02 +0000 (UTC) Date: Fri, 19 Jun 2020 17:53:59 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Lukas Straub Subject: Re: [PATCH v4 1/4] Introduce yank feature Message-ID: <20200619165359.GC700896@redhat.com> References: <20200616143957.GF550360@redhat.com> <20200619162350.5a1cb518@luklap> MIME-Version: 1.0 In-Reply-To: <20200619162350.5a1cb518@luklap> User-Agent: Mutt/1.14.0 (2020-05-02) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 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-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/19 02:45:39 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN 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 , qemu-block , Juan Quintela , qemu-devel , Max Reitz , Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jun 19, 2020 at 04:23:50PM +0200, Lukas Straub wrote: > On Tue, 16 Jun 2020 15:39:57 +0100 > Daniel P. Berrangé wrote: > > > On Mon, May 25, 2020 at 05:44:23PM +0200, Lukas Straub wrote: > > > The yank feature allows to recover from hanging qemu by "yanking" > > > at various parts. Other qemu systems can register themselves and > > > multiple yank functions. Then all yank functions for selected > > > instances can be called by the 'yank' out-of-band qmp command. > > > Available instances can be queried by a 'query-yank' oob command. > > > > > > Signed-off-by: Lukas Straub > > > --- > > > qapi/misc.json | 45 +++++++++++++ > > > yank.c | 174 +++++++++++++++++++++++++++++++++++++++++++++++++ > > > yank.h | 67 +++++++++++++++++++ > > > 3 files changed, 286 insertions(+) > > > create mode 100644 yank.c > > > create mode 100644 yank.h > > > > > +void yank_register_function(char *instance_name, YankFn *func, void *opaque) > > > +{ > > > + struct YankInstance *instance; > > > + struct YankFuncAndParam *entry; > > > + > > > + qemu_mutex_lock(&lock); > > > + instance = yank_find_instance(instance_name); > > > + assert(instance); > > > + > > > + entry = g_slice_new(struct YankFuncAndParam); > > > + entry->func = func; > > > + entry->opaque = opaque; > > > + > > > + QLIST_INSERT_HEAD(&instance->yankfns, entry, next); > > > + qemu_mutex_unlock(&lock); > > > +} > > > + > > > +void yank_unregister_function(char *instance_name, YankFn *func, void *opaque) > > > +{ > > > + struct YankInstance *instance; > > > + struct YankFuncAndParam *entry; > > > + > > > + qemu_mutex_lock(&lock); > > > + instance = yank_find_instance(instance_name); > > > + assert(instance); > > > + > > > + QLIST_FOREACH(entry, &instance->yankfns, next) { > > > + if (entry->func == func && entry->opaque == opaque) { > > > + QLIST_REMOVE(entry, next); > > > + g_slice_free(struct YankFuncAndParam, entry); > > > + qemu_mutex_unlock(&lock); > > > + return; > > > + } > > > + } > > > + > > > + abort(); > > > +} > > > > Since the NBD impl no longer needs to register multiple different functions > > on the same insance_nane, these methods could be be simplified, to only > > accept a single function, instead of keeping a whole list. This would avoid > > need to pass a function into the unregister() method at all. > > Multiple yank functions are still needed for multifd migration. Oh I missed that subtlety, so fine to ignore my suggestion. 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 :|