drm: Move master pointer from drm_minor to drm_device
There can only be one current master, and it's for the overall device. Render/control minors don't support master-based auth at all. This simplifies the master logic a lot, at least in my eyes: All these additional pointer chases are just confusing. While doing the conversion I spotted some locking fail: - drm_lock/drm_auth check dev->master without holding the master_mutex. This is fallout from commit c996fd0b Author: Thomas Hellstrom <thellstrom@vmware.com> Date: Tue Feb 25 19:57:44 2014 +0100 drm: Protect the master management with a drm_device::master_mutex v3 but I honestly don't care one bit about those old legacy drivers using this. - debugfs name info should just grab master_mutex. - And the fbdev helper looked at it to figure out whether someone is using KMS. We just need a consistent value, so READ_ONCE. Aside: We should probably check if anyone has opened a control node too, but I guess current userspace doesn't really do that yet. v2: Balance locking, reported by Julia. v3: Rebase on top of Chris' oops fixes. Cc: Julia Lawall <julia.lawall@lip6.fr> Cc: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v2) Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com> (v2) Signed-off-by:Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-1-git-send-email-daniel.vetter@ffwll.ch
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