From: Gustavo Padovan <gustavo@padovan.org>
To: Rob Clark <robdclark@gmail.com>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>,
dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] dma-buf/fence-array: fix deadlock in fence-array
Date: Mon, 17 Oct 2016 16:52:48 -0200 [thread overview]
Message-ID: <20161017185248.GB11538@joana> (raw)
In-Reply-To: <1476729612-22602-1-git-send-email-robdclark@gmail.com>
2016-10-17 Rob Clark <robdclark@gmail.com>:
> Currently with fence-array, we have a potential deadlock situation. If we
> fence_add_callback() on an array-fence, the array-fence's lock is acquired
> first, and in it's ->enable_signaling() callback, it will install cb's on
> it's array-member fences, so the array-member's lock is acquired second.
>
> But in the signal path, the array-member's lock is acquired first, and the
> array-fence's lock acquired second.
>
> To solve that, always enabling signaling up-front (in the fence_array
> constructor) without the fence_array's lock held.
Do we always want to enable signaling for arrays? One of the things we
removed from the Sync Framework was the need to enable signalling at
creation time.
Just merging fencing doesn't mean you want signaling, that is supposed
to happen only when poll() is called on the sync file.
Gustavo
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next prev parent reply other threads:[~2016-10-17 18:52 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 18:40 [PATCH] dma-buf/fence-array: fix deadlock in fence-array Rob Clark
2016-10-17 18:52 ` Gustavo Padovan [this message]
2016-10-17 18:59 ` Rob Clark
2016-10-17 19:26 ` Gustavo Padovan
2016-10-17 19:39 ` Chris Wilson
2016-10-17 19:44 ` Gustavo Padovan
2016-10-18 7:41 ` Daniel Vetter
2016-10-18 11:49 ` Rob Clark
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