Re: drm: gem_object_free without struct_mutex

[Dan Carpenter <error27@gmail.com>]

On Wed, Dec 30, 2009 at 11:17:48PM +0100, Rafael J. Wysocki wrote:
> [CC to Jesse.]
> 
> On Wednesday 30 December 2009, Hugh Dickins wrote:
> > I've changed BUG_ON to WARN_ON in drm_gem.c (patch at bottom) to
> > get this dmesg when I resume after suspend, instead of crashing.
> > 
> > Perhaps it's a patch that should go in, perhaps not, but obviously
> > the real problem lies elsewhere.  Happens with 2.6.33-rc1 and -rc2.
> > 
> > No surprise if I'm stupidly misconfigured to get the "pin power context"
> > error in the first place (.config on demand), but I don't deserve to BUG!
> > 

The problem is dev_priv->mm.suspended which was set in i915_suspend().

In i915_resume()

   107          i915_restore_state(dev);

The i915_restore_state() fails because i915_gem_object_bind_to_gtt()
does this:

        if (dev_priv->mm.suspended)
                return -EBUSY;

   108  
   109          intel_opregion_init(dev, 1);
   110  
   111          /* KMS EnterVT equivalent */
   112          if (drm_core_check_feature(dev, DRIVER_MODESET)) {
   113                  mutex_lock(&dev->struct_mutex);
   114                  dev_priv->mm.suspended = 0;

We do set the dev_priv->mm.suspended here but it's too late.

Not sure the fix though...

regards,
dan carpenter