• Daniel Vetter's avatar
    drm: Move master pointer from drm_minor to drm_device · 95c081c1
    Daniel Vetter authored
    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: default avatarDaniel Vetter <daniel.vetter@intel.com>
    Link: http://patchwork.freedesktop.org/patch/msgid/1466499262-18717-1-git-send-email-daniel.vetter@ffwll.ch
    95c081c1
drm_fb_helper.c 62.4 KB