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xen/gntdev: Do not destroy context while dma-bufs are in use

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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@epam.com>
Reviewed-by: Boris Ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Oleksandr Andrushchenko
2019-02-14 16:23:20 +02:00
committed by Juergen Gross
parent 7681f31ec9
commit fa13e665e0
3 changed files with 13 additions and 3 deletions
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2
drivers/xen/gntdev.c
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@@ -600,7 +600,7 @@ static int gntdev_open(struct inode *inode, struct file *flip)
mutex_init(&priv->lock);
#ifdef CONFIG_XEN_GNTDEV_DMABUF
priv->dmabuf_priv = gntdev_dmabuf_init();
priv->dmabuf_priv = gntdev_dmabuf_init(flip);
if (IS_ERR(priv->dmabuf_priv)) {
ret = PTR_ERR(priv->dmabuf_priv);
kfree(priv);