linux-kernel - Re: [Xen-devel][PATCH 1/2] xen/gntdev: Do not destroy context while dma-bufs are in use

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Date:   Sun, 17 Feb 2019 11:39:41 +0100
From:   Juergen Gross <jgross@...e.com>
To:     Oleksandr Andrushchenko <andr2000@...il.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        boris.ostrovsky@...cle.com
Cc:     Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [Xen-devel][PATCH 1/2] xen/gntdev: Do not destroy context while
 dma-bufs are in use

On 14/02/2019 15:23, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
> 
> If there are exported DMA buffers which are still in use and
> grant device is closed by either normal user-space close or by
> a signal this leads to the grant device context to be destroyed,
> thus making it not possible to correctly destroy those exported
> buffers when they are returned back to gntdev and makes the module
> crash:
> 
> [  339.617540] [<ffff00000854c0d8>] dmabuf_exp_ops_release+0x40/0xa8
> [  339.617560] [<ffff00000867a6e8>] dma_buf_release+0x60/0x190
> [  339.617577] [<ffff0000082211f0>] __fput+0x88/0x1d0
> [  339.617589] [<ffff000008221394>] ____fput+0xc/0x18
> [  339.617607] [<ffff0000080ed4e4>] task_work_run+0x9c/0xc0
> [  339.617622] [<ffff000008089714>] do_notify_resume+0xfc/0x108
> 
> Fix this by referencing gntdev on each DMA buffer export and
> unreferencing on buffer release.
> 
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>

Applied to xen/tip.git for-linus-5.1


Juergen