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Date: Thu, 14 Mar 2019 11:02:12 -0400 From: Boris Ostrovsky <boris.ostrovsky@...cle.com> To: Oleksandr Andrushchenko <andr2000@...il.com>, netdev@...r.kernel.org, xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org, jgross@...e.com, sstabellini@...nel.org, davem@...emloft.net Cc: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>, Volodymyr Babchuk <Volodymyr_Babchuk@...m.com> Subject: Re: [Xen-devel][PATCH] xen/netfront: Remove unneeded .resume callback On 3/14/19 10:52 AM, Oleksandr Andrushchenko wrote: > On 3/14/19 4:47 PM, Boris Ostrovsky wrote: >> On 3/14/19 9:17 AM, Oleksandr Andrushchenko wrote: >>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com> >>> >>> Currently on driver resume we remove all the network queues and >>> destroy shared Tx/Rx rings leaving the driver in its current state >>> and never signaling the backend of this frontend's state change. >>> This leads to the number of consequences: >>> - when frontend withdraws granted references to the rings etc. it >>> cannot >>> be cleanly done as the backend still holds those (it was not told to >>> free the resources) >>> - it is not possible to resume driver operation as all the >>> communication >>> means with the backned were destroyed by the frontend, thus >>> making the frontend appear to the guest OS as functional, but >>> not really. >> >> What do you mean? Are you saying that after resume you lose >> connectivity? > Exactly, if you take a look at the .resume callback as it is now > what it does it destroys the rings etc. and never notifies the backend > of that, e.g. it stays in, say, connected state with communication > channels destroyed. It never goes into any other Xen bus state, so > there is > no way its state machine can help recovering. My tree is about a month old so perhaps there is some sort of regression but this certainly works for me. After resume netfront gets XenbusStateInitWait from backend which causes xennet_connect(). -boris
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