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Chasing plane->state->crtc of planes that are *not* part of the same
atomic update is racy, making it incredibly awkward (or impossible) to
do something simple like iterate over all planes and figure out which
ones are attached to a crtc.
Solve this by adding a bitmask of currently attached planes in the
crtc-state.
Note that the transitional helpers do not maintain the plane_mask. But
they only support the legacy ioctls, which have sufficient brute-force
locking around plane updates that they can continue to loop over all
planes to see what is attached to a crtc the old way.
Signed-off-by: Rob Clark <robdclark@gmail.com>
[danvet:
- Drop comments about locking in set_crtc_for_plane since they're a
bit misleading - we already should hold lock for the current crtc.
- Also WARN_ON if get_state on the old crtc fails since that should
have been done already.
- Squash in fixup to check get_plane_state return value, reported by
Dan Carpenter and acked by Rob Clark.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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I've forgotten to remove that in my per-plane locking patch.
Reported-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
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This is an oversight from
commit f52b69f1ecfdd7ef6867a257620258c09e569552
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Wed Nov 19 18:38:08 2014 +0100
drm/atomic: Don't overrun the connector array when hotplugging
Cc: Dave Airlie <airlied@redhat.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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Yet another fallout from not considering DP MST hotplug. With the
previous patches we have stable indices, but it might still happen
that a connector gets added between when we allocate the array and
when we actually add a connector. Especially when we back off due to
ww mutex contention or similar issues.
So store the sizes of the arrays in struct drm_atomic_state and double
check them. We don't really care about races except that we want to
use a consistent value, so ACCESS_ONCE is all we need. And if we
indeed notice that we'd overrun the array then just give up and
restart the entire ioctl.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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Otherwise the connector might have been unplugged and destroyed while
we didn't look. Yet another fallout from DP MST hotplugging that I
didn't consider.
To make sure we get this right add an appropriate WARN_ON to
drm_atomic_state_clear (obviously only when we actually have a state
to clear up). And reorder all the state_clear and backoff calls to
make it work out properly.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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I've totally forgotten that with DP MST connectors can now be
hotplugged. And failed to adapt Rob's drm_atomic_state code (which
predates connector hotplugging) to the new realities.
The first step is to make sure that the connector indices used to
access the arrays of pointers are stable. The connection mutex gives
us enough guarantees for that, which means we won't unecessarily block
on concurrent modesets or background probing.
So add a locking WARN_ON and shuffle the code slightly to make sure we
always hold the right lock.
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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Turned out to be much simpler on top of my latest atomic stuff than
what I've feared. Some details:
- Drop the modeset_lock_all snakeoil in drm_plane_init. Same
justification as for the equivalent change in drm_crtc_init done in
commit d0fa1af40e784aaf7ebb7ba8a17b229bb3fa4c21
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Sep 8 09:02:49 2014 +0200
drm: Drop modeset locking from crtc init function
Without these the drm_modeset_lock_init would fall over the exact
same way.
- Since the atomic core code wraps the locking switching it to
per-plane locks was a one-line change.
- For the legacy ioctls add a plane argument to the locking helper so
that we can grab the right plane lock (cursor or primary). Since the
universal cursor plane might not be there, or someone really crazy
might forgoe the primary plane even accept NULL.
- Add some locking WARN_ON to the atomic helpers for good paranoid
measure and to check that it all works out.
Tested on my exynos atomic hackfest with full lockdep checks and ww
backoff injection.
v2: I've forgotten about the load-detect code in i915.
v3: Thierry reported that in latest 3.18-rc vmwgfx doesn't compile any
more due to
commit 21e88620aa21b48d4f62d29275e3e2944a5ea2b5
Author: Rob Clark <robdclark@gmail.com>
Date: Thu Oct 30 13:39:04 2014 -0400
drm/vmwgfx: fix lock breakage
Rebased and fix this up.
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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So my original plan was that the drm core refcounts framebuffers like
with the legacy ioctls. But that doesn't work for a bunch of reasons:
- State objects might live longer than until the next fb change
happens for a plane. For example delayed cleanup work only happens
_after_ the pageflip ioctl has completed. So this definitely doesn't
work without the plane state holding its own references.
- The other issue is transition from legacy to atomic implementations,
where the driver works under a mix of both worlds. Which means
legacy paths might not properly update the ->fb pointer under
plane->state->fb. Which is a bit a problem when then someone comes
around and _does_ try to clean it up when it's long gone.
The second issue is just a bit a transition bug, since drivers should
update plane->state->fb in all the paths that aren't converted yet.
But a bit more robustness for the transition can't hurt - we pull
similar tricks with cleaning up the old fb in the transitional helpers
already.
The pattern for drivers that transition is
if (plane->state)
drm_atomic_set_fb_for_plane(plane->state, plane->fb);
inserted after the fb update has logically completed at the end of
->set_config (or ->set_base/mode_set if using the crtc helpers),
->page_flip, ->update_plane or any other entry point which updates
plane->fb.
v2: Update kerneldoc - copypasta fail.
v3: Fix spelling in the commit message (Sean).
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
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Some differences compared to Rob's patches again:
- Dropped the committed and checked booleans. Checking will be
internally enforced by always calling ->atomic_check before
->atomic_commit. And async handling needs to be solved differently
because the current scheme completely side-steps ww mutex deadlock
avoidance (and so either reinvents a new deadlock avoidance wheel or
like the current code just deadlocks).
- State for connectors needed to be added, since now they have a
full-blown drm_connector_state (so that drivers have something to
attach their own stuff to).
- Refcounting is gone. I plane to solve async updates differently,
since the lock-passing scheme doesn't cut it (since it abuses ww
mutexes). Essentially what we need for async is a simple ownership
transfer from the caller to the driver. That doesn't need full-blown
refcounting.
- The acquire ctx is a pointer. Real atomic callers should have that
on their stack, legacy entry points need to put the right one
(obtained by drm_modeset_legacy_acuire_ctx) in there.
- I've dropped all hooks except check/commit. All the begin/end
handling is done by core functions and is the same.
- commit/check are just thin wrappers that ensure that ->check is
always called.
- To help out with locking in the legacy implementations I've added a
helper to just grab all locks in the backoff case.
v2: Add notices that check/commit can fail with EDEADLK.
v3:
- More consistent naming for state_alloc.
- Add state_clear which is needed for backoff and retry.
v4: Planes/connectors can switch between crtcs, and we need to be
careful that we grab the state (and locks) for both the old and new
crtc. Improve the interface functions to ensure this.
v5: Add functions to grab affected connectors for a crtc and to recompute
the crtc->enable state. This is useful for both helper and atomic ioctl
code when e.g. removing a connector.
v6: Squash in fixup from Fengguang to use ERR_CAST.
v7: Add debug output.
v8: Make checkpatch happy about kcalloc argument ordering.
v9: Improve kerneldoc in drm_crtc.h
v10:
- Fix another kcalloc argument misorder I've missed.
- More polish for kerneldoc.
v11: Clarify the ownership rules for the state object. The new rule is
that a successful drm_atomic_commit (whether synchronous or asnyc)
always inherits the state and is responsible for the clean-up. That
way async and sync ->commit functions are more similar.
v12: A few bugfixes:
- Assign state->state pointers correctly when grabbing state objects -
we need to link them up with the global state.
- Handle a NULL crtc in set_crtc_for_plane to simplify code flow a bit
for the callers of this function.
v13: Review from Sean:
- kerneldoc spelling fixes
- Don't overallocate states->planes.
- Handle NULL crtc in set_crtc_for_connector.
v14: Sprinkle __must_check over all functions which do wait/wound
locking to make sure callers don't forget this. Since I have ;-)
v15: Be more explicit in the kerneldoc when functions can return
-EDEADLK what to do. And that every other -errno is fatal.
v16: Indent with tabs instead of space, spotted by Ander.
v17: Review from Thierry, small kerneldoc and other naming polish.
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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