RE: [PATCH] [REPOST for the char-misc-linus branch] Drivers: hv: vmbus: Offload the handling of channels to two workqueues

From: Dexuan Cui <decui@microsoft.com>
To: Sasha Levin <sashal@kernel.org>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"apw@canonical.com" <apw@canonical.com>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	KY Srinivasan <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>
Subject: RE: [PATCH] [REPOST for the char-misc-linus branch] Drivers: hv: vmbus: Offload the handling of channels to two workqueues
Date: Tue, 4 Dec 2018 09:05:02 +0000	[thread overview]
Message-ID: <PU1P153MB01695594453C53F95B6F0D9FBFAF0@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <20181204085734.GQ235790@sasha-vm>

> From: Sasha Levin <sashal@kernel.org>
> Sent: Tuesday, December 4, 2018 12:58 AM
> To: Dexuan Cui <decui@microsoft.com>
> Cc: gregkh@linuxfoundation.org; apw@canonical.com; stable@vger.kernel.org;
> Stephen Hemminger <sthemmin@microsoft.com>; KY Srinivasan
> <kys@microsoft.com>; Haiyang Zhang <haiyangz@microsoft.com>
> Subject: Re: [PATCH] [REPOST for the char-misc-linus branch] Drivers: hv: vmbus:
> Offload the handling of channels to two workqueues
> 
> On Mon, Dec 03, 2018 at 08:11:18PM +0000, Dexuan Cui wrote:
> >> From: Sasha Levin <sashal@kernel.org>
> >> Sent: Monday, December 3, 2018 6:16 AM
> >>
> >> Hi,
> >>
> >> [This is an automated email]
> >>
> >> This commit has been processed because it contains a "Fixes:" tag,
> >> fixing commit: 8195b1396ec8 hv_netvsc: fix deadlock on hotplug.
> >>
> >> The bot has tested the following trees: v4.19.6, v4.14.85,
> >>
> >> v4.19.6: Build OK!
> >> v4.14.85: Failed to apply! Possible dependencies:
> >>     50229128727f ("Drivers: hv: vmbus: Fix the offer_in_progress in
> >> vmbus_process_offer()")
> >>     c2e5df616e1a ("vmbus: add per-channel sysfs info")
> >>
> >> How should we proceed with this patch?
> >> Sasha
> >
> >BTW, the patch went into char-misc.git's char-misc-linus branch 13 hours ago:
> >37c2578c0c40 ("Drivers: hv: vmbus: Offload the handling of channels to two
> workqueues")
> >
> >linux-4.14.y (v4.14.85) lacks c2e5df616e1a ("vmbus: add per-channel sysfs
> info")
> >and the other related patches so this patch can't apply cleanly.
> >
> >I suggest we cherry-pick all the related patches to linux-4.14.y in this order:
> >
> >(Note: 37c2578c0c40 is in char-misc.git's char-misc-linus branch and is not in
> Linus's tree yet)
> >
> >c2e5df616e1a ("vmbus: add per-channel sysfs info")
> >869b5567e12f ("vmbus: unregister device_obj->channels_kset")
> >6712cc9c2211 ("vmbus: don't return values for uninitalized channels")
> >50229128727f ("Drivers: hv: vmbus: Fix the offer_in_progress in
> vmbus_process_offer()")
> >37c2578c0c40 ("Drivers: hv: vmbus: Offload the handling of channels to two
> workqueues")
> >
> >
> >Alternatively, we can skip c2e5df616e1a ("vmbus: add per-channel sysfs info"),
> and then
> >please use the attached rebased patch for v4.14.85.
> >
> >
> >I prefer the first solution.
> 
> Why is c2e5df616e1a needed on 4.14? We usually prefer to take a
> dependency or two to avoid custom backports, but a sysfs ABI change
> which causes only trivial conflicts for the actual fix is a bit too
> much.
> 
> --
> Thanks,
> Sasha

Thanks for the explanation. Then I'm fine with the second solution. I attached
For-v4.14.85-0001-Drivers-hv-vmbus-Offload-the-handling-of-channels-to.patch
in a prior mail for v4.14.85.

Thanks,
-- Dexuan