[Intel-gfx] [PATCH] drm/atomic: Fix outdated comment.

[Daniel Vetter]

On Wed, Jan 04, 2017 at 11:22:54AM +0000, Chris Wilson wrote:
> On Wed, Jan 04, 2017 at 12:15:55PM +0100, Maarten Lankhorst wrote:
> > Op 15-12-16 om 16:19 schreef Daniel Vetter:
> > > On Thu, Dec 15, 2016 at 03:29:42PM +0100, Maarten Lankhorst wrote:
> > >> drm_atomic_state_put is called unconditionally, so TEST_ONLY is no
> > >> different from commit.
> > >>
> > >> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > > I think it'd be good to update the kerneldoc for the atomic_commit
> > > callback to mention that drivers should grab their own references using
> > > drm_atomic_state_get() when they need it.
> > >
> > > Applied this one meanwhile, thanks.
> > 
> > --->8---
> > Commit 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
> > adds reference counting to atomic state, but didn't update the comments
> > in drm_atomic_(nonblocking_)commit. Clarify lifetime a bit more.
> > 
> > Fixes: 0853695c3ba4 ("drm: Add reference counting to drm_atomic_state")
> > Cc: <drm-intel-fixes at lists.freedesktop.org> # v4.10-rc1+
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > ---
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 681d5f97639d..6492546476b4 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -1599,10 +1599,9 @@ EXPORT_SYMBOL(drm_atomic_check_only);
> >   * more locks but encountered a deadlock. The caller must then do the usual w/w
> >   * backoff dance and restart. All other errors are fatal.
> >   *
> > - * Also note that on successful execution ownership of @state is transferred
> > - * from the caller of this function to the function itself. The caller must not
> > - * free or in any other way access @state. If the function fails then the caller
> > - * must clean up @state itself.
> > + * In earlier versions of the atomic api, the caller was handing its reference
> > + * of @state over to this function on success. This is no longer the case, and
> > + * callers should always call drm_atomic_state_put().
> >   *
> >   * Returns:
> >   * 0 on success, negative error code on failure.
> > @@ -1630,10 +1629,9 @@ EXPORT_SYMBOL(drm_atomic_commit);
> >   * more locks but encountered a deadlock. The caller must then do the usual w/w
> >   * backoff dance and restart. All other errors are fatal.
> >   *
> > - * Also note that on successful execution ownership of @state is transferred
> > - * from the caller of this function to the function itself. The caller must not
> > - * free or in any other way access @state. If the function fails then the caller
> > - * must clean up @state itself.
> > + * In earlier versions of the atomic api, the caller was handing its reference
> > + * of @state over to this function on success. This is no longer the case, and
> > + * callers should always call drm_atomic_state_put().
> 
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> 
> But do we really want the confusion of mentioning what the api doesn't do
> any more?

Agreed, kerneldoc should state what is (and why), maybe with a FIXME if it
only makes sense with some hystorical context and what should be done
instead. git blame is for figuring out what was.

Maarten, can you pls respin?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch