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drm/rockchip: Don't grab dev->struct_mutex for in mmap offset ioctl 

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.

v2: Fixup compile fail 0-day spotted.

Cc: Mark Yao <mark.yao@rock-chips.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
hifive-unleashed-5.1
Daniel Vetter 2015-07-09 23:32:42 +02:00
parent 141518b64f
commit 648a4ce7ca
1 changed files with 4 additions and 8 deletions
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12
drivers/gpu/drm/rockchip/rockchip_drm_gem.c
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@ -200,13 +200,10 @@ int rockchip_gem_dumb_map_offset(struct drm_file *file_priv,
struct drm_gem_object *obj;
int ret;
mutex_lock(&dev->struct_mutex);
obj = drm_gem_object_lookup(dev, file_priv, handle);
if (!obj) {
DRM_ERROR("failed to lookup gem object.\n");
ret = -EINVAL;
goto unlock;
return -EINVAL;
}
ret = drm_gem_create_mmap_offset(obj);
@ -217,10 +214,9 @@ int rockchip_gem_dumb_map_offset(struct drm_file *file_priv,
DRM_DEBUG_KMS("offset = 0x%llx\n", *offset);
out:
drm_gem_object_unreference(obj);
unlock:
mutex_unlock(&dev->struct_mutex);
return ret;
drm_gem_object_unreference_unlocked(obj);
return 0;
}
/*