[PATCH] drm/atomic: Handle -EDEADLK with out-fences correctly

[Gustavo Padovan]

2017-08-14 Maarten Lankhorst <maarten.lankhorst at linux.intel.com>:

> complete_crtc_signaling is freeing fence_state, but when retrying
> num_fences and fence_state are not zero'd. This caused duplicate
> fd's in the fence_state array, followed by a BUG_ON in fs/file.c
> because we reallocate freed memory, and installing over an existing
> fd, or potential other fun.
> 
> Zero fence_state and num_fences correctly in the retry loop, which
> allows kms_atomic_transition to pass.
> 
> Fixes: beaf5af48034 ("drm/fence: add out-fences support")
> Cc: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
> Cc: Brian Starkey <brian.starkey at arm.com> (v10)
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: David Airlie <airlied at linux.ie>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> Cc: <stable at vger.kernel.org> # v4.10+
> Testcase: kms_atomic_transitions.plane-all-modeset-transition-fencing
> (with CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y)
> ---
>  drivers/gpu/drm/drm_atomic.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Reviewed-by: Gustavo Padovan <gustavo.padovan at collabora.com>

	Gustavo