We want to make sure that no one tries to acquire more locks and states, and ww mutexes provide debug facilities for that. So use them.
Cc: Rob Clark robdclark@gmail.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Signed-off-by: Daniel Vetter daniel.vetter@intel.com --- drivers/gpu/drm/drm_atomic.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 422183e7ee7d..5ea609f270ea 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -1268,6 +1268,8 @@ int drm_atomic_check_only(struct drm_atomic_state *state) } }
+ ww_acquire_done(&state->acquire_ctx->ww_ctx); + return ret; } EXPORT_SYMBOL(drm_atomic_check_only);
On Wed, Aug 5, 2015 at 4:57 PM, Maarten Lankhorst maarten.lankhorst@linux.intel.com wrote:
What would blow up? This should only be called fairly late in the transition when most of the atomic handling is correctly done. And i915 is probably the most extreme example of a conversion, so if it works out for us I think everyone else should be fine too.
Generally drivers only started to do fancy stuff with get_*_state once converted to atomic to start exploiting it, not before the transition is completed. i915 is different since we have a lot of our own modeset code ... -Daniel
Op 05-08-15 om 17:03 schreef Daniel Vetter:
Might blow up with transitional helpers, though not 100% sure if it would.
Also if atomic_check returns -EDEADLK you would still say acquire_done, that will definitely blow up in legitimate cases..
If it doesn't blow up transitional helpers and you fix the -EDEADLK, acked-by. :-)
Should we electrify drm_atomic_get_{*}_state too, to force everyone to use the get_existing_state versions?
~Maarten
On Wed, Aug 5, 2015 at 8:13 PM, Maarten Lankhorst maarten.lankhorst@linux.intel.com wrote:
Transitional helpers don't use the top-level atomic_commit/check entry points and hence don't use this function here at all.
Also if atomic_check returns -EDEADLK you would still say acquire_done, that will definitely blow up in legitimate cases..
If it doesn't blow up transitional helpers and you fix the -EDEADLK, acked-by. :-)
Yeah that needs to be fixed ;-)
And I think this is the killer - we unconditionally take the locks again, taking advantage of -EALREADY. But with this patch that will blow and we need to patch up all the existing code to use the get_existing_state functions. That will be a bigger series I guess ...
I'll make a note about this and defer this for now. But the get_*_state vs. get_existing_*_state thing will actually make these two functions more distinctive, so I think this patch here will be really useful. But needs driver fixes and kerneldoc updates too. -Daniel
Op 06-08-15 om 00:25 schreef Daniel Vetter:
After some sleep I think only when ret == 0 we should call acquire_done.
Depends, this only happens when the object can not be found in the state the locks are taken for planes and crtc's. But it seems for connectors it happens unconditionally.
I think this is fine; grabbing existing state for crtc's and planes will work and grabbing new state during atomic_commit is a bug anyway. The only driver that uses drm_atomic_get_connector_state is i915, which uses it for the setup phase.
~Maarten
On Thu, Aug 06, 2015 at 06:17:28AM +0200, Maarten Lankhorst wrote:
Yeah I've done a full audit too, everything seems to be fine. -Daniel
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