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| author | Maarten Lankhorst <maarten.lankhorst@linux.intel.com> | 2016-05-03 11:12:31 +0200 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2016-05-03 14:35:45 +0200 |
| commit | 7f4eaa89fb20d9fd178d2f9db5aa2df5af358dcd (patch) | |
| tree | f4d9f9ec6f002c86f7c36fc38aa3a605b4e86930 | |
| parent | drm/fsl-dcu: add COMMON_CLK dependency (diff) | |
| download | linux-7f4eaa89fb20d9fd178d2f9db5aa2df5af358dcd.tar.xz linux-7f4eaa89fb20d9fd178d2f9db5aa2df5af358dcd.zip | |
drm/atomic: Add WARN_ON when state->acquire_ctx is not set.
When I was writing an atomic wrapper for rmfb, I ran into the
following backtrace from lockdep:
=============================================
[ INFO: possible recursive locking detected ]
4.5.0-patser+ #4696 Tainted: G U
---------------------------------------------
kworker/2:2/2608 is trying to acquire lock:
(crtc_ww_class_mutex){+.+.+.}, at: [<ffffffffc00c9ddc>] drm_modeset_lock+0x7c/0x120 [drm]
but task is already holding lock:
(crtc_ww_class_mutex){+.+.+.}, at: [<ffffffffc00c98cd>] modeset_backoff+0x8d/0x220 [drm]
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(crtc_ww_class_mutex);
lock(crtc_ww_class_mutex);
*** DEADLOCK ***
May be due to missing lock nesting notation
4 locks held by kworker/2:2/2608:
#0: ("events"){.+.+.+}, at: [<ffffffff810a5eea>] process_one_work+0x15a/0x6c0
#1: ((&arg.work)){+.+.+.}, at: [<ffffffff810a5eea>] process_one_work+0x15a/0x6c0
#2: (crtc_ww_class_acquire){+.+.+.}, at: [<ffffffffc004532a>] drm_atomic_helper_remove_fb+0x4a/0x1d0 [drm_kms_helper]
#3: (crtc_ww_class_mutex){+.+.+.}, at: [<ffffffffc00c98cd>] modeset_backoff+0x8d/0x220 [drm]
While lockdep probably catches this bug when it happens, it's better
to explicitly warn when state->acquire_ctx is not set.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462266751-29123-1-git-send-email-maarten.lankhorst@linux.intel.com
| -rw-r--r-- | drivers/gpu/drm/drm_atomic.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 0b526423f19f..69adcf3944cc 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -263,6 +263,8 @@ drm_atomic_get_crtc_state(struct drm_atomic_state *state, int ret, index = drm_crtc_index(crtc); struct drm_crtc_state *crtc_state; + WARN_ON(!state->acquire_ctx); + crtc_state = drm_atomic_get_existing_crtc_state(state, crtc); if (crtc_state) return crtc_state; @@ -622,6 +624,8 @@ drm_atomic_get_plane_state(struct drm_atomic_state *state, int ret, index = drm_plane_index(plane); struct drm_plane_state *plane_state; + WARN_ON(!state->acquire_ctx); + plane_state = drm_atomic_get_existing_plane_state(state, plane); if (plane_state) return plane_state; @@ -890,6 +894,8 @@ drm_atomic_get_connector_state(struct drm_atomic_state *state, struct drm_mode_config *config = &connector->dev->mode_config; struct drm_connector_state *connector_state; + WARN_ON(!state->acquire_ctx); + ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx); if (ret) return ERR_PTR(ret); |