[Intel-gfx] [PATCH v2] drm/atomic: Handle vblank events in atomic ioctl correctly.
Maarten Lankhorst
maarten.lankhorst at linux.intel.com
Mon Jun 15 01:42:44 PDT 2015
Op 15-06-15 om 08:22 schreef Daniel Vetter:
> On Tue, Jun 02, 2015 at 09:00:46AM +0200, Maarten Lankhorst wrote:
>> All users of async updates seem to clear clear crtc_state->event
>> correctly, so move destroying vblank event to crtc_destroy_state.
>>
>> This is better than manually free'ing it in the atomic ioctl, since
>> this code seems to do it wrong.
>>
>> While we're at it handle -EDEADLK from atomic_commit correctly,
>> because the check might fail otherwise if it takes additional state.
> Please don't smash unrelated fixes together into the same patch.
>
>> Changes since v1:
>> - Fix freeing a NULL framebuffer, thanks for catching Daniel Stone.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
>> Reviewed-by: Daniel Stone <daniels at collabora.com>
>> ---
>> drivers/gpu/drm/drm_atomic.c | 45 +++++++++----------------------------
>> drivers/gpu/drm/drm_atomic_helper.c | 15 +++++++++++++
>> 2 files changed, 26 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
>> index c7e59b074e62..8add0dd8dc5d 100644
>> --- a/drivers/gpu/drm/drm_atomic.c
>> +++ b/drivers/gpu/drm/drm_atomic.c
>> @@ -1328,17 +1328,6 @@ out:
>> return e;
>> }
>>
>> -static void destroy_vblank_event(struct drm_device *dev,
>> - struct drm_file *file_priv, struct drm_pending_vblank_event *e)
>> -{
>> - unsigned long flags;
>> -
>> - spin_lock_irqsave(&dev->event_lock, flags);
>> - file_priv->event_space += sizeof e->event;
>> - spin_unlock_irqrestore(&dev->event_lock, flags);
>> - kfree(e);
>> -}
>> -
>> static int atomic_set_prop(struct drm_atomic_state *state,
>> struct drm_mode_object *obj, struct drm_property *prop,
>> uint64_t prop_value)
>> @@ -1534,13 +1523,18 @@ retry:
>> if (arg->flags & DRM_MODE_ATOMIC_TEST_ONLY) {
>> ret = drm_atomic_check_only(state);
>> /* _check_only() does not free state, unlike _commit() */
>> - drm_atomic_state_free(state);
>> + if (!ret)
>> + drm_atomic_state_free(state);
>> } else if (arg->flags & DRM_MODE_ATOMIC_NONBLOCK) {
>> ret = drm_atomic_async_commit(state);
>> } else {
>> ret = drm_atomic_commit(state);
>> }
>>
>> +fail:
>> + if (ret == -EDEADLK)
>> + goto backoff;
>> +
>> /* if succeeded, fixup legacy plane crtc/fb ptrs before dropping
>> * locks (ie. while it is still safe to deref plane->state). We
>> * need to do this here because the driver entry points cannot
>> @@ -1553,32 +1547,15 @@ retry:
>> drm_framebuffer_reference(new_fb);
>> plane->fb = new_fb;
>> plane->crtc = plane->state->crtc;
>> - } else {
>> - plane->old_fb = NULL;
>> - }
>> - if (plane->old_fb) {
>> - drm_framebuffer_unreference(plane->old_fb);
>> - plane->old_fb = NULL;
>> - }
>> - }
>> -
>> - drm_modeset_drop_locks(&ctx);
>> - drm_modeset_acquire_fini(&ctx);
>> -
>> - return ret;
>> -
>> -fail:
>> - if (ret == -EDEADLK)
>> - goto backoff;
> We have a pre-existing bug here already of leaking plane->old_fb before
> dropping locks. I think the EDEADLK case needs to be after the cleanup
> loop to clear old_fb.
>
Ok, I'll send a fix for that first.
It's also bugged because old_fb is assigned before the plane lock is taken, resulting in possible memory corruption or leaks.
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