On Tue, Nov 11, 2014 at 10:12:00AM +0100, Daniel Vetter wrote:
> 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@xxxxxxxx>
> 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@xxxxxxxxx>
> Date: Thu Oct 30 13:39:04 2014 -0400
>
> drm/vmwgfx: fix lock breakage
>
> Rebased and fix this up.
>
> Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
One minor nit about avoiding the recursive lock handling in drm_modeset_lock. I
am fine with the patch either way.
Reviewed-by: Sean Paul <seanpaul@xxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic.c | 2 +-
> drivers/gpu/drm/drm_atomic_helper.c | 4 ++++
> drivers/gpu/drm/drm_crtc.c | 9 ++++----
> drivers/gpu/drm/drm_modeset_lock.c | 43 +++++++++++++++++++++++++++---------
> drivers/gpu/drm/i915/intel_display.c | 6 +++++
> drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 4 ++--
> include/drm/drm_crtc.h | 2 ++
> include/drm/drm_modeset_lock.h | 4 +++-
> 8 files changed, 55 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index ed991ba66e21..ed22a719440f 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -244,7 +244,7 @@ drm_atomic_get_plane_state(struct drm_atomic_state *state,
> * grab all crtc locks. Once we have per-plane locks we must update this
> * to only take the plane mutex.
> */
> - ret = drm_modeset_lock_all_crtcs(state->dev, state->acquire_ctx);
> + ret = drm_modeset_lock(&plane->mutex, state->acquire_ctx);
> if (ret)
> return ERR_PTR(ret);
>
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index ca839bd9bb0d..2526de8e6cbe 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -995,6 +995,8 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
> if (!crtc)
> continue;
>
> + WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
> +
> funcs = crtc->helper_private;
>
> if (!funcs || !funcs->atomic_begin)
> @@ -1010,6 +1012,8 @@ void drm_atomic_helper_commit_planes(struct drm_device *dev,
> if (!plane)
> continue;
>
> + WARN_ON(!drm_modeset_is_locked(&plane->mutex));
> +
> funcs = plane->helper_private;
>
> if (!funcs || !funcs->atomic_update)
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index e6c169152bf1..3652ed8dda80 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -1152,12 +1152,12 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
> {
> int ret;
>
> - drm_modeset_lock_all(dev);
> -
> ret = drm_mode_object_get(dev, &plane->base, DRM_MODE_OBJECT_PLANE);
> if (ret)
> goto out;
>
> + drm_modeset_lock_init(&plane->mutex);
> +
> plane->base.properties = &plane->properties;
> plane->dev = dev;
> plane->funcs = funcs;
> @@ -1185,7 +1185,6 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
> plane->type);
>
> out:
> - drm_modeset_unlock_all(dev);
>
> return ret;
> }
> @@ -2809,7 +2808,7 @@ static int drm_mode_cursor_common(struct drm_device *dev,
> * If this crtc has a universal cursor plane, call that plane's update
> * handler rather than using legacy cursor handlers.
> */
> - drm_modeset_lock_crtc(crtc);
> + drm_modeset_lock_crtc(crtc, crtc->cursor);
> if (crtc->cursor) {
> ret = drm_mode_cursor_universal(crtc, req, file_priv);
> goto out;
> @@ -4598,7 +4597,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
> if (!crtc)
> return -ENOENT;
>
> - drm_modeset_lock_crtc(crtc);
> + drm_modeset_lock_crtc(crtc, crtc->primary);
> if (crtc->primary->fb == NULL) {
> /* The framebuffer is currently unbound, presumably
> * due to a hotplug event, that userspace has not
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
> index 474e4d12a2d8..51cc47d827d8 100644
> --- a/drivers/gpu/drm/drm_modeset_lock.c
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -157,14 +157,20 @@ void drm_modeset_unlock_all(struct drm_device *dev)
> EXPORT_SYMBOL(drm_modeset_unlock_all);
>
> /**
> - * drm_modeset_lock_crtc - lock crtc with hidden acquire ctx
> - * @crtc: drm crtc
> + * drm_modeset_lock_crtc - lock crtc with hidden acquire ctx for a plane update
> + * @crtc: DRM CRTC
> + * @plane: DRM plane to be updated on @crtc
> + *
> + * This function locks the given crtc and plane (which should be either the
> + * primary or cursor plane) using a hidden acquire context. This is necessary so
> + * that drivers internally using the atomic interfaces can grab further locks
> + * with the lock acquire context.
> *
> - * This function locks the given crtc using a hidden acquire context. This is
> - * necessary so that drivers internally using the atomic interfaces can grab
> - * further locks with the lock acquire context.
> + * Note that @plane can be NULL, e.g. when the cursor support hasn't yet been
> + * converted to universal planes yet.
> */
> -void drm_modeset_lock_crtc(struct drm_crtc *crtc)
> +void drm_modeset_lock_crtc(struct drm_crtc *crtc,
> + struct drm_plane *plane)
> {
> struct drm_modeset_acquire_ctx *ctx;
> int ret;
> @@ -180,6 +186,18 @@ retry:
> if (ret)
> goto fail;
>
> + if (plane) {
> + ret = drm_modeset_lock(&plane->mutex, ctx);
> + if (ret)
> + goto fail;
> +
> + if (plane->crtc) {
nit: if you check plane->crtc != crtc here, you can save from going through the
ww error handling code as well as avoiding the modeset_lock -EALREADY safety net
> + ret = drm_modeset_lock(&plane->crtc->mutex, ctx);
> + if (ret)
> + goto fail;
> + }
> + }
> +
> WARN_ON(crtc->acquire_ctx);
>
> /* now we hold the locks, so now that it is safe, stash the
> @@ -437,15 +455,14 @@ void drm_modeset_unlock(struct drm_modeset_lock *lock)
> }
> EXPORT_SYMBOL(drm_modeset_unlock);
>
> -/* Temporary.. until we have sufficiently fine grained locking, there
> - * are a couple scenarios where it is convenient to grab all crtc locks.
> - * It is planned to remove this:
> - */
> +/* In some legacy codepaths it's convenient to just grab all the crtc and plane
> + * related locks. */
> int drm_modeset_lock_all_crtcs(struct drm_device *dev,
> struct drm_modeset_acquire_ctx *ctx)
> {
> struct drm_mode_config *config = &dev->mode_config;
> struct drm_crtc *crtc;
> + struct drm_plane *plane;
> int ret = 0;
>
> list_for_each_entry(crtc, &config->crtc_list, head) {
> @@ -454,6 +471,12 @@ int drm_modeset_lock_all_crtcs(struct drm_device *dev,
> return ret;
> }
>
> + list_for_each_entry(plane, &config->plane_list, head) {
> + ret = drm_modeset_lock(&plane->mutex, ctx);
> + if (ret)
> + return ret;
> + }
> +
> return 0;
> }
> EXPORT_SYMBOL(drm_modeset_lock_all_crtcs);
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 728869d640c8..7f747a7ac0d3 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -8563,6 +8563,9 @@ retry:
> ret = drm_modeset_lock(&crtc->mutex, ctx);
> if (ret)
> goto fail_unlock;
> + ret = drm_modeset_lock(&crtc->primary->mutex, ctx);
> + if (ret)
> + goto fail_unlock;
>
> old->dpms_mode = connector->dpms;
> old->load_detect_temp = false;
> @@ -8600,6 +8603,9 @@ retry:
> ret = drm_modeset_lock(&crtc->mutex, ctx);
> if (ret)
> goto fail_unlock;
> + ret = drm_modeset_lock(&crtc->primary->mutex, ctx);
> + if (ret)
> + goto fail_unlock;
> intel_encoder->new_crtc = to_intel_crtc(crtc);
> to_intel_connector(connector)->new_encoder = intel_encoder;
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index 941a7bc0b791..3725b521d931 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -252,7 +252,7 @@ int vmw_du_crtc_cursor_set(struct drm_crtc *crtc, struct drm_file *file_priv,
> ret = 0;
> out:
> drm_modeset_unlock_all(dev_priv->dev);
> - drm_modeset_lock_crtc(crtc);
> + drm_modeset_lock_crtc(crtc, crtc->cursor);
>
> return ret;
> }
> @@ -281,7 +281,7 @@ int vmw_du_crtc_cursor_move(struct drm_crtc *crtc, int x, int y)
> du->cursor_y + du->hotspot_y);
>
> drm_modeset_unlock_all(dev_priv->dev);
> - drm_modeset_lock_crtc(crtc);
> + drm_modeset_lock_crtc(crtc, crtc->cursor);
>
> return 0;
> }
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index d82238c5b9d8..8739e8fcf038 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -771,6 +771,8 @@ struct drm_plane {
> struct drm_device *dev;
> struct list_head head;
>
> + struct drm_modeset_lock mutex;
> +
> struct drm_mode_object base;
>
> uint32_t possible_crtcs;
> diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
> index 28931a23d96c..70595ff565ba 100644
> --- a/include/drm/drm_modeset_lock.h
> +++ b/include/drm/drm_modeset_lock.h
> @@ -127,11 +127,13 @@ void drm_modeset_unlock(struct drm_modeset_lock *lock);
>
> struct drm_device;
> struct drm_crtc;
> +struct drm_plane;
>
> void drm_modeset_lock_all(struct drm_device *dev);
> int __drm_modeset_lock_all(struct drm_device *dev, bool trylock);
> void drm_modeset_unlock_all(struct drm_device *dev);
> -void drm_modeset_lock_crtc(struct drm_crtc *crtc);
> +void drm_modeset_lock_crtc(struct drm_crtc *crtc,
> + struct drm_plane *plane);
> void drm_modeset_unlock_crtc(struct drm_crtc *crtc);
> void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
> struct drm_modeset_acquire_ctx *
> --
> 2.1.1
>
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