> -----Original Message----- > From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > Sent: Wednesday, January 28, 2015 20:09 PM > To: Dexuan Cui > Cc: KY Srinivasan; devel@xxxxxxxxxxxxxxxxxxxxxx; Haiyang Zhang; linux- > kernel@xxxxxxxxxxxxxxx; Jason Wang; Radim Krčmář; Dan Carpenter > Subject: Re: [PATCH v3 3/3] Drivers: hv: vmbus: serialize Offer and Rescind > offer > > Dexuan Cui <decui@xxxxxxxxxxxxx> writes: > > >> -----Original Message----- > >> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx] > >> Sent: Tuesday, January 20, 2015 23:45 PM > >> To: KY Srinivasan; devel@xxxxxxxxxxxxxxxxxxxxxx > >> Cc: Haiyang Zhang; linux-kernel@xxxxxxxxxxxxxxx; Dexuan Cui; Jason Wang; > >> Radim Krčmář; Dan Carpenter > >> Subject: [PATCH v3 3/3] Drivers: hv: vmbus: serialize Offer and Rescind > offer > ... > > > > Hi Vitaly and all, > > I have 2 questions: > > In vmbus_process_offer(), in the cases of "goto err_free_chan", > > should we consider the possibility a rescind message could be pending for > > the new channel? > > In the cases, because we don't run > > "INIT_WORK(&newchannel->work, vmbus_process_rescind_offer); ", > > vmbus_onoffer_rescind() will do nothing and as a result, > > vmbus_process_rescind_offer() won't be invoked. > > Yes, but processing the rescind offer results in freeing the channel > (and this processing supposes the channel wasn't freed before) so > there is no difference... or is it? > > > > > Question 2: in vmbus_process_offer(), in the case > > vmbus_device_register() fails, we'll run > > "list_del(&newchannel->listentry);" -- just after this line, > > what will happen at this time if relid2channel() returns NULL > > in vmbus_onoffer_rescind()? > > > > I think we'll lose the rescind message. > > > > Yes, but same logic applies - we already freed the channes so no rescind > proccessing required. free_channel() and vmbus_process_rescind_offer() are different, because the latter does more work, e.g., sending the host a message CHANNELMSG_RELID_RELEASED. In the cases of "goto err_free_chan" + "a pending rescind message", the host may expect the message CHANNELMSG_RELID_RELEASED and could reoffer the channel once the message is received. It would be better if the VM doesn't lose the rescind message here. :-) > If we still need to do something we need to > add support for already freed channel to the rescind offer processing path. > Thanks, -- Dexuan _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
