linux-kernel - Re: [RFC 26/29] dma-buf/fence: remove pointless fence_timeline

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Date:	Thu, 25 Feb 2016 12:26:47 -0300
From:	Gustavo Padovan <gustavo@...ovan.org>
To:	Tom Cherry <tomcherry@...gle.com>
Cc:	Greg Hackmann <ghackmann@...gle.com>,
	Gustavo Padovan <gustavo.padovan@...labora.co.uk>,
	John Harrison <John.C.Harrison@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org, devel@...verdev.osuosl.org,
	dri-devel@...ts.freedesktop.org, daniels@...labora.com,
	Arve Hjønnevåg <arve@...roid.com>,
	Riley Andrews <riandrews@...roid.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	Rob Clark <robdclark@...il.com>,
	Maarten Lankhorst <maarten.lankhorst@...onical.com>,
	Dmitry Torokhov <dtor@...gle.com>
Subject: Re: [RFC 26/29] dma-buf/fence: remove pointless
 fence_timeline_signal at destroy phase

2016-02-09 Tom Cherry <tomcherry@...gle.com>:

> On Fri, Jan 15, 2016 at 3:42 PM, Greg Hackmann <ghackmann@...gle.com> wrote:
> > On 01/15/2016 10:02 AM, Gustavo Padovan wrote:
> >>
> >> Patches 27 and 28 are attempt to fix that. I assumed that if some code is
> >> calling fence_timeline_destroy() it wants to stop everything so I
> >> worked on a solution that stops any waiter and allows the timeline to be
> >> destroyed.
> >>
> >> No one is using fence_timeline_destroy() in mainline now, so it is
> >> definately a behaviour we can discuss.
> >>
> >>         Gustavo
> >>
> >
> > +Tom Cherry and Dmitry Torokhov recently discovered that this was broken by
> > the refactoring of Android sync on top of dma-buf fences.
> >
> > Tom and Dmitry, did you send the proposed fix upstream?
> 
> There was a similar issue that I had originally thought to be related
> to fence_timeline_destroy() but was actually related to
> sync_fence_free().  Dmitry sent the patch upstream at
> https://lkml.org/lkml/2015/12/14/953, but it does not look like it has
> received any feedback.
> 
> We saw real panics without this patch.  I didn't see this patch or any
> similar changes in the destaging commits, and I would recommend it be
> looked at while destaging this driver.

This patch is already uptream, Greg pushed it in December. :)

	Gustavo