On Fri, Nov 16, 2018 at 7:44 PM Sean Paul sean@poorly.run wrote:
From: Sean Paul seanpaul@chromium.org
Add modeset lock checks to functions that could be called outside the core atomic stack.
Changes in v2:
- None
Signed-off-by: Sean Paul seanpaul@chromium.org
drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 2 ++ drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 1 + 2 files changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c index a008a87a8113..cd0a0bea4335 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c @@ -284,6 +284,8 @@ enum dpu_intf_mode dpu_crtc_get_intf_mode(struct drm_crtc *crtc) return INTF_MODE_NONE; }
WARN_ON(!drm_modeset_is_locked(&crtc->mutex));/* TODO: Returns the first INTF_MODE, could there be multiple values? */ drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask) return dpu_encoder_get_intf_mode(encoder);diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c index 64134d619748..5104fc01147e 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c @@ -358,6 +358,7 @@ void dpu_kms_encoder_enable(struct drm_encoder *encoder) if (funcs && funcs->commit) funcs->commit(encoder);
WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex)); drm_for_each_crtc(crtc, dev) { if (!(crtc->state->encoder_mask & drm_encoder_mask(encoder))) continue;
I'm fairly sure this is called in the atomic_commit path, and in there you might not actually hold these locks (if you do a nonblocking modeset).
The locking rules for ->state are pretty fun: Either hold the lock, or be in atomic commit. In the later case atomic helpers' commit ordering guarantees that you can safely access ->state (but read-only only) without hodling any locks. You might want to revert.
Don't ask why I stumbled over this. -Daniel