drm: Switch blobs to the new generic modeset obj refcounting
Need to move the free function around a bit, but otherwise mostly just removing code. Specifically we can nuke all the _locked variants since the weak idr reference is now protected by the idr_mutex, which we never hold anywhere expect in the lookup/reg/unreg functions. And those never call anything else. Another benefit of this is that this patch switches the weak reference logic from kref_put_mutex to kref_get_unless_zero. And the later is in general more flexible wrt accomodating multiple weak references protected by different locks, which might or might not come handy eventually. But one consequence of that switch is that we need to acquire the blob_lock from the free function for the list_del calls. That's a bit tricky to pull off, but works well if we pick the exact same scheme as is already used for framebuffers. Most important changes: - filp list is maintainer by create/destroy_blob ioctls directly (already the case, so we can just remove the redundant list_del from the free function). - filp close handler walks the filp-private list lockless - works because we know no one else can access it. I copied the same comment from the fb code over to explain this. - Otherwise we need to sufficiently restrict blob_lock critical sections to avoid all the unreference calls. Easy to do once the blob_lock only protects the list, and no longer the weak reference. Cc: Dave Airlie <airlied@gmail.com> Cc: Daniel Stone <daniels@collabora.com> Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com> Signed-off-by: NDave Airlie <airlied@redhat.com>
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