[PATCH 10/18] drm/rockchip: Don't grab dev->struct_mutex for in mmap offset ioctl

[Thierry Reding]

On Thu, Jul 09, 2015 at 11:32:42PM +0200, Daniel Vetter wrote:
> Since David Herrmann's mmap vma manager rework we don't need to grab
> dev->struct_mutex any more to prevent races when looking up the mmap
> offset. Drop it and instead don't forget to use the unref_unlocked
> variant (since the drm core still cares).
> 
> Aside: I stumbled over the mmap handler which directly does a
> dma_mmap_attrs. But totally fails to grab a reference on the
> underlying object and hence looks like it happily just leaks the ptes
> since there's no guarantee the mmap isn't still around when
> gem_free_object is called. Which the kerneldoc of dma_mmap_attrs
> explicitly forbids.

Same is true for Exynos, which seems to be the source for copy/paste
here.

Anyway, for this change:

Reviewed-by: Thierry Reding <treding at nvidia.com>
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