On Wed, May 28, 2014 at 07:57:25PM -0400, Rob Clark wrote:
> For atomic, it will be quite necessary to not need to care so much
> about locking order. And 'state' gives us a convenient place to stash a
> ww_ctx for any sort of update that needs to grab multiple crtc locks.
>
> Because we will want to eventually make locking even more fine grained
> (giving locks to planes, connectors, etc), split out drm_modeset_lock
> and drm_modeset_acquire_ctx to track acquired locks.
>
> Atomic will use this to keep track of which locks have been acquired
> in a transaction.
>
> Signed-off-by: Rob Clark <robdclark at gmail.com>
I still would like to see all the additional magic for atomic updates
removed from the drm_mode_lock functions. Getting the w/w dance right
isn't that simple and all these complications confuse.
Also I simply can't review whether these added features make sense without
their users ;-)
-Daniel
> ---
> drivers/gpu/drm/Makefile | 2 +-
> drivers/gpu/drm/drm_crtc.c | 87 +++++++++++-----
> drivers/gpu/drm/drm_crtc_helper.c | 3 +-
> drivers/gpu/drm/drm_fb_helper.c | 4 +
> drivers/gpu/drm/drm_modeset_lock.c | 187
> +++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/drm_plane_helper.c | 2 +-
> drivers/gpu/drm/i915/intel_crt.c | 5 +-
> drivers/gpu/drm/i915/intel_display.c | 58 +++++++----
> drivers/gpu/drm/i915/intel_drv.h | 6 +-
> drivers/gpu/drm/i915/intel_sprite.c | 2 +-
> drivers/gpu/drm/i915/intel_tv.c | 5 +-
> drivers/gpu/drm/omapdrm/omap_crtc.c | 10 +-
> drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 8 +-
> include/drm/drmP.h | 5 -
> include/drm/drm_crtc.h | 15 +--
> include/drm/drm_modeset_lock.h | 139 ++++++++++++++++++++++++++
> include/uapi/drm/drm_mode.h | 3 +
> 17 files changed, 468 insertions(+), 73 deletions(-)
> create mode 100644 drivers/gpu/drm/drm_modeset_lock.c
> create mode 100644 include/drm/drm_modeset_lock.h
>
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 48e38ba..bf4c12d 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -14,7 +14,7 @@ drm-y := drm_auth.o drm_buffer.o drm_bufs.o
> drm_cache.o \
> drm_info.o drm_debugfs.o drm_encoder_slave.o \
> drm_trace_points.o drm_global.o drm_prime.o \
> drm_rect.o drm_vma_manager.o drm_flip_work.o \
> - drm_plane_helper.o
> + drm_plane_helper.o drm_modeset_lock.o
>
> drm-$(CONFIG_COMPAT) += drm_ioc32.o
> drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index de1520c..cf622f6 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -37,8 +37,8 @@
> #include <drm/drm_crtc.h>
> #include <drm/drm_edid.h>
> #include <drm/drm_fourcc.h>
> +#include <drm/drm_modeset_lock.h>
>
> -#include "drm_crtc_internal.h"
>
> /**
> * drm_modeset_lock_all - take all modeset locks
> @@ -50,14 +50,42 @@
> */
> void drm_modeset_lock_all(struct drm_device *dev)
> {
> - struct drm_crtc *crtc;
> + struct drm_mode_config *config = &dev->mode_config;
> + struct drm_modeset_acquire_ctx *ctx;
> + int ret;
>
> - mutex_lock(&dev->mode_config.mutex);
> + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> + if (WARN_ON(!ctx))
> + return;
>
> - mutex_lock(&dev->mode_config.connection_mutex);
> + mutex_lock(&config->mutex);
>
> - list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> - mutex_lock_nest_lock(&crtc->mutex, &dev->mode_config.mutex);
> + drm_modeset_acquire_init(ctx, false, false);
> +
> +retry:
> + ret = drm_modeset_lock(&config->connection_mutex, ctx);
> + if (ret)
> + goto fail;
> + ret = drm_modeset_lock_all_crtcs(dev, ctx);
> + if (ret)
> + goto fail;
> +
> + WARN_ON(config->acquire_ctx);
> +
> + /* now we hold the locks, so now that it is safe, stash the
> + * ctx for drm_modeset_unlock_all():
> + */
> + config->acquire_ctx = ctx;
> +
> + drm_warn_on_modeset_not_all_locked(dev);
> +
> + return;
> +
> +fail:
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(ctx);
> + goto retry;
> + }
> }
> EXPORT_SYMBOL(drm_modeset_lock_all);
>
> @@ -69,12 +97,18 @@ EXPORT_SYMBOL(drm_modeset_lock_all);
> */
> void drm_modeset_unlock_all(struct drm_device *dev)
> {
> - struct drm_crtc *crtc;
> + struct drm_mode_config *config = &dev->mode_config;
> + struct drm_modeset_acquire_ctx *ctx = config->acquire_ctx;
>
> - list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> - mutex_unlock(&crtc->mutex);
> + if (WARN_ON(!ctx))
> + return;
> +
> + config->acquire_ctx = NULL;
> + drm_modeset_drop_locks(ctx);
> + ww_acquire_fini(&ctx->ww_ctx);
> + drm_modeset_acquire_fini(ctx);
>
> - mutex_unlock(&dev->mode_config.connection_mutex);
> + kfree(ctx);
>
> mutex_unlock(&dev->mode_config.mutex);
> }
> @@ -95,9 +129,9 @@ void drm_warn_on_modeset_not_all_locked(struct drm_device
> *dev)
> return;
>
> list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
> - WARN_ON(!mutex_is_locked(&crtc->mutex));
> + WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
>
> - WARN_ON(!mutex_is_locked(&dev->mode_config.connection_mutex));
> + WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
> }
> EXPORT_SYMBOL(drm_warn_on_modeset_not_all_locked);
> @@ -677,6 +711,8 @@ void drm_framebuffer_remove(struct drm_framebuffer *fb)
> }
> EXPORT_SYMBOL(drm_framebuffer_remove);
>
> +DEFINE_WW_CLASS(crtc_ww_class);
> +
> /**
> * drm_crtc_init_with_planes - Initialise a new CRTC object with
> * specified primary and cursor planes.
> @@ -696,6 +732,7 @@ int drm_crtc_init_with_planes(struct drm_device *dev,
> struct drm_crtc *crtc,
> void *cursor,
> const struct drm_crtc_funcs *funcs)
> {
> + struct drm_mode_config *config = &dev->mode_config;
> int ret;
>
> crtc->dev = dev;
> @@ -703,8 +740,9 @@ int drm_crtc_init_with_planes(struct drm_device *dev,
> struct drm_crtc *crtc,
> crtc->invert_dimensions = false;
>
> drm_modeset_lock_all(dev);
> - mutex_init(&crtc->mutex);
> - mutex_lock_nest_lock(&crtc->mutex, &dev->mode_config.mutex);
> + drm_modeset_lock_init(&crtc->mutex);
> + /* dropped by _unlock_all(): */
> + drm_modeset_lock(&crtc->mutex, config->acquire_ctx);
>
> ret = drm_mode_object_get(dev, &crtc->base, DRM_MODE_OBJECT_CRTC);
> if (ret)
> @@ -712,8 +750,8 @@ int drm_crtc_init_with_planes(struct drm_device *dev,
> struct drm_crtc *crtc,
>
> crtc->base.properties = &crtc->properties;
>
> - list_add_tail(&crtc->head, &dev->mode_config.crtc_list);
> - dev->mode_config.num_crtc++;
> + list_add_tail(&crtc->head, &config->crtc_list);
> + config->num_crtc++;
>
> crtc->primary = primary;
> if (primary)
> @@ -741,6 +779,8 @@ void drm_crtc_cleanup(struct drm_crtc *crtc)
> kfree(crtc->gamma_store);
> crtc->gamma_store = NULL;
>
> + drm_modeset_lock_fini(&crtc->mutex);
> +
> drm_mode_object_put(dev, &crtc->base);
> list_del(&crtc->head);
> dev->mode_config.num_crtc--;
> @@ -1804,7 +1844,7 @@ int drm_mode_getconnector(struct drm_device *dev, void
> *data,
> DRM_DEBUG_KMS("[CONNECTOR:%d:?]\n", out_resp->connector_id);
>
> mutex_lock(&dev->mode_config.mutex);
> - mutex_lock(&dev->mode_config.connection_mutex);
> + drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>
> connector = drm_connector_find(dev, out_resp->connector_id);
> if (!connector) {
> @@ -1903,7 +1943,7 @@ int drm_mode_getconnector(struct drm_device *dev, void
> *data,
> out_resp->count_encoders = encoders_count;
>
> out:
> - mutex_unlock(&dev->mode_config.connection_mutex);
> + drm_modeset_unlock(&dev->mode_config.connection_mutex);
> mutex_unlock(&dev->mode_config.mutex);
>
> return ret;
> @@ -2487,7 +2527,7 @@ static int drm_mode_cursor_common(struct drm_device
> *dev,
> return -ENOENT;
> }
>
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
> if (req->flags & DRM_MODE_CURSOR_BO) {
> if (!crtc->funcs->cursor_set && !crtc->funcs->cursor_set2) {
> ret = -ENXIO;
> @@ -2511,7 +2551,7 @@ static int drm_mode_cursor_common(struct drm_device
> *dev,
> }
> }
> out:
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
>
> return ret;
>
> @@ -4195,7 +4235,7 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev,
> if (!crtc)
> return -ENOENT;
>
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
> if (crtc->primary->fb == NULL) {
> /* The framebuffer is currently unbound, presumably
> * due to a hotplug event, that userspace has not
> @@ -4279,7 +4319,7 @@ out:
> drm_framebuffer_unreference(fb);
> if (old_fb)
> drm_framebuffer_unreference(old_fb);
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
>
> return ret;
> }
> @@ -4644,7 +4684,7 @@ EXPORT_SYMBOL(drm_format_vert_chroma_subsampling);
> void drm_mode_config_init(struct drm_device *dev)
> {
> mutex_init(&dev->mode_config.mutex);
> - mutex_init(&dev->mode_config.connection_mutex);
> + drm_modeset_lock_init(&dev->mode_config.connection_mutex);
> mutex_init(&dev->mode_config.idr_mutex);
> mutex_init(&dev->mode_config.fb_lock);
> INIT_LIST_HEAD(&dev->mode_config.fb_list);
> @@ -4744,5 +4784,6 @@ void drm_mode_config_cleanup(struct drm_device *dev)
> }
>
> idr_destroy(&dev->mode_config.crtc_idr);
> + drm_modeset_lock_fini(&dev->mode_config.connection_mutex);
> }
> EXPORT_SYMBOL(drm_mode_config_cleanup);
> diff --git a/drivers/gpu/drm/drm_crtc_helper.c
> b/drivers/gpu/drm/drm_crtc_helper.c
> index 5b93caf..4eaded8 100644
> --- a/drivers/gpu/drm/drm_crtc_helper.c
> +++ b/drivers/gpu/drm/drm_crtc_helper.c
> @@ -89,8 +89,7 @@ bool drm_helper_encoder_in_use(struct drm_encoder *encoder)
> struct drm_device *dev = encoder->dev;
>
> WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
> - WARN_ON(!mutex_is_locked(&dev->mode_config.connection_mutex));
> -
> + WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
> list_for_each_entry(connector, &dev->mode_config.connector_list, head)
> if (connector->encoder == encoder)
> return true;
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 1e28ba6..25f687d 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -355,6 +355,10 @@ static bool drm_fb_helper_force_kernel_mode(void)
> if (dev->switch_power_state == DRM_SWITCH_POWER_OFF)
> continue;
>
> + /* NOTE: we use lockless flag below to avoid grabbing other
> + * modeset locks. So just trylock the underlying mutex
> + * directly:
> + */
> if (!mutex_trylock(&dev->mode_config.mutex)) {
> error = true;
> continue;
> diff --git a/drivers/gpu/drm/drm_modeset_lock.c
> b/drivers/gpu/drm/drm_modeset_lock.c
> new file mode 100644
> index 0000000..6580d6c
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_modeset_lock.c
> @@ -0,0 +1,187 @@
> +/*
> + * Copyright (C) 2014 Red Hat
> + * Author: Rob Clark <robdclark at gmail.com>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#include <drm/drmP.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_modeset_lock.h>
> +
> +
> +void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
> + bool nolock, bool nonblock)
> +{
> + ww_acquire_init(&ctx->ww_ctx, &crtc_ww_class);
> + INIT_LIST_HEAD(&ctx->locked);
> + mutex_init(&ctx->mutex);
> + ctx->nolock = nolock;
> + ctx->nonblock = nonblock;
> +}
> +EXPORT_SYMBOL(drm_modeset_acquire_init);
> +
> +void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx)
> +{
> + WARN_ON(ctx->contended);
> + /*
> + * NOTE: it is intentional that ww_acquire_fini() is not called
> + * here.. due to the way lock handover works in drm_atomic
> + */
> + mutex_destroy(&ctx->mutex);
> +}
> +EXPORT_SYMBOL(drm_modeset_acquire_fini);
> +
> +void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx)
> +{
> + WARN_ON(ctx->contended);
> + mutex_lock(&ctx->mutex);
> + while (!list_empty(&ctx->locked)) {
> + struct drm_modeset_lock *lock;
> +
> + lock = list_first_entry(&ctx->locked,
> + struct drm_modeset_lock, head);
> +
> + drm_modeset_unlock(lock);
> + }
> + mutex_unlock(&ctx->mutex);
> +}
> +EXPORT_SYMBOL(drm_modeset_drop_locks);
> +
> +static int modeset_lock(struct drm_modeset_lock *lock,
> + struct drm_modeset_acquire_ctx *ctx,
> + bool interruptible, bool slow)
> +{
> + int ret;
> +
> + if (ctx->nolock)
> + return 0;
> +
> + WARN_ON(ctx->frozen); /* all locks should be held by now! */
> + WARN_ON(ctx->contended);
> +
> +retry:
> + if (interruptible) {
> + ret = ww_mutex_lock_interruptible(&lock->mutex, &ctx->ww_ctx);
> + } else if (slow) {
> + ww_mutex_lock_slow(&lock->mutex, &ctx->ww_ctx);
> + ret = 0;
> + } else {
> + ret = ww_mutex_lock(&lock->mutex, &ctx->ww_ctx);
> + }
> + if (!ret) {
> + if (lock->atomic_pending) {
> + /* some other pending update with dropped locks */
> + ww_mutex_unlock(&lock->mutex);
> + if (ctx->nonblock)
> + return -EBUSY;
> + wait_event(lock->event, !lock->atomic_pending);
> + goto retry;
> + }
> + lock->atomic_pending = true;
> + WARN_ON(!list_empty(&lock->head));
> + list_add(&lock->head, &ctx->locked);
> + } else if (ret == -EALREADY) {
> + /* we already hold the lock.. this is fine */
> + ret = 0;
> + } else if (ret == -EDEADLK) {
> + ctx->contended = lock;
> + }
> +
> + return ret;
> +}
> +
> +void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx)
> +{
> + struct drm_modeset_lock *contended = ctx->contended;
> +
> + ctx->contended = NULL;
> +
> + if (WARN_ON(!contended))
> + return;
> +
> + drm_modeset_drop_locks(ctx);
> +
> + modeset_lock(contended, ctx, false, true);
> +}
> +EXPORT_SYMBOL(drm_modeset_backoff);
> +
> +/**
> + * drm_modeset_lock - take modeset lock
> + * @lock: lock to take
> + * @ctx: acquire ctx
> + *
> + * If ctx is not NULL, then then it's acquire context is used
> + * and the lock does not need to be explicitly unlocked, it
> + * will be automatically unlocked when the atomic update is
> + * complete
> + */
> +int drm_modeset_lock(struct drm_modeset_lock *lock,
> + struct drm_modeset_acquire_ctx *ctx)
> +{
> + if (ctx)
> + return modeset_lock(lock, ctx, false, false);
> +
> + ww_mutex_lock(&lock->mutex, NULL);
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_modeset_lock);
> +
> +int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
> + struct drm_modeset_acquire_ctx *ctx)
> +{
> + if (ctx)
> + return modeset_lock(lock, ctx, true, false);
> +
> + return ww_mutex_lock_interruptible(&lock->mutex, NULL);
> +}
> +EXPORT_SYMBOL(drm_modeset_lock_interruptible);
> +
> +/**
> + * drm_modeset_unlock - drop modeset lock
> + * @lock: lock to release
> + */
> +void drm_modeset_unlock(struct drm_modeset_lock *lock)
> +{
> + list_del_init(&lock->head);
> + lock->atomic_pending = false;
> + ww_mutex_unlock(&lock->mutex);
> + wake_up_all(&lock->event);
> +}
> +EXPORT_SYMBOL(drm_modeset_unlock);
> +
> +/**
> + * drm_modeset_lock_all_crtcs - helper to drm_modeset_lock() all CRTCs
> + */
> +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;
> + int ret = 0;
> +
> + list_for_each_entry(crtc, &config->crtc_list, head) {
> + ret = drm_modeset_lock(&crtc->mutex, ctx);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_modeset_lock_all_crtcs);
> diff --git a/drivers/gpu/drm/drm_plane_helper.c
> b/drivers/gpu/drm/drm_plane_helper.c
> index 458d9bf..6301ec6 100644
> --- a/drivers/gpu/drm/drm_plane_helper.c
> +++ b/drivers/gpu/drm/drm_plane_helper.c
> @@ -59,7 +59,7 @@ static int get_connectors_for_crtc(struct drm_crtc *crtc,
> * need to grab the connection_mutex here to be able to make these
> * checks.
> */
> - WARN_ON(!mutex_is_locked(&dev->mode_config.connection_mutex));
> + WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
>
> list_for_each_entry(connector, &dev->mode_config.connector_list, head)
> if (connector->encoder && connector->encoder->crtc == crtc) {
> diff --git a/drivers/gpu/drm/i915/intel_crt.c
> b/drivers/gpu/drm/i915/intel_crt.c
> index 22d8347..33328fc 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -630,6 +630,7 @@ intel_crt_detect(struct drm_connector *connector, bool
> force)
> enum intel_display_power_domain power_domain;
> enum drm_connector_status status;
> struct intel_load_detect_pipe tmp;
> + struct drm_modeset_acquire_ctx ctx;
>
> intel_runtime_pm_get(dev_priv);
>
> @@ -673,12 +674,12 @@ intel_crt_detect(struct drm_connector *connector, bool
> force)
> }
>
> /* for pre-945g platforms use load detect */
> - if (intel_get_load_detect_pipe(connector, NULL, &tmp)) {
> + if (intel_get_load_detect_pipe(connector, NULL, &tmp, &ctx)) {
> if (intel_crt_detect_ddc(connector))
> status = connector_status_connected;
> else
> status = intel_crt_load_detect(crt);
> - intel_release_load_detect_pipe(connector, &tmp);
> + intel_release_load_detect_pipe(connector, &tmp, &ctx);
> } else
> status = connector_status_unknown;
>
> diff --git a/drivers/gpu/drm/i915/intel_display.c
> b/drivers/gpu/drm/i915/intel_display.c
> index 5844f07..ba6cbbb 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -2363,7 +2363,7 @@ void intel_display_handle_reset(struct drm_device *dev)
> list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
> struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
>
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
> /*
> * FIXME: Once we have proper support for primary planes (and
> * disabling them without disabling the entire crtc) allow again
> @@ -2374,7 +2374,7 @@ void intel_display_handle_reset(struct drm_device *dev)
>
> crtc->primary->fb,
> crtc->x,
> crtc->y);
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
> }
> }
>
> @@ -7972,7 +7972,8 @@ mode_fits_in_fbdev(struct drm_device *dev,
>
> bool intel_get_load_detect_pipe(struct drm_connector *connector,
> struct drm_display_mode *mode,
> - struct intel_load_detect_pipe *old)
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct intel_crtc *intel_crtc;
> struct intel_encoder *intel_encoder =
> @@ -7982,13 +7983,19 @@ bool intel_get_load_detect_pipe(struct drm_connector
> *connector,
> struct drm_crtc *crtc = NULL;
> struct drm_device *dev = encoder->dev;
> struct drm_framebuffer *fb;
> - int i = -1;
> + struct drm_mode_config *config = &dev->mode_config;
> + int ret, i = -1;
>
> DRM_DEBUG_KMS("[CONNECTOR:%d:%s], [ENCODER:%d:%s]\n",
> connector->base.id, drm_get_connector_name(connector),
> encoder->base.id, drm_get_encoder_name(encoder));
>
> - mutex_lock(&dev->mode_config.connection_mutex);
> + drm_modeset_acquire_init(ctx, false, false);
> +
> +retry:
> + ret = drm_modeset_lock(&config->connection_mutex, ctx);
> + if (ret)
> + goto fail_unlock;
>
> /*
> * Algorithm gets a little messy:
> @@ -8004,7 +8011,9 @@ bool intel_get_load_detect_pipe(struct drm_connector
> *connector,
> if (encoder->crtc) {
> crtc = encoder->crtc;
>
> - mutex_lock(&crtc->mutex);
> + ret = drm_modeset_lock(&crtc->mutex, ctx);
> + if (ret)
> + goto fail_unlock;
>
> old->dpms_mode = connector->dpms;
> old->load_detect_temp = false;
> @@ -8017,7 +8026,7 @@ bool intel_get_load_detect_pipe(struct drm_connector
> *connector,
> }
>
> /* Find an unused one (if possible) */
> - list_for_each_entry(possible_crtc, &dev->mode_config.crtc_list, head) {
> + list_for_each_entry(possible_crtc, &config->crtc_list, head) {
> i++;
> if (!(encoder->possible_crtcs & (1 << i)))
> continue;
> @@ -8032,10 +8041,12 @@ bool intel_get_load_detect_pipe(struct drm_connector
> *connector,
> */
> if (!crtc) {
> DRM_DEBUG_KMS("no pipe available for load-detect\n");
> - goto fail_unlock_connector;
> + goto fail_unlock;
> }
>
> - mutex_lock(&crtc->mutex);
> + ret = drm_modeset_lock(&crtc->mutex, ctx);
> + if (ret)
> + goto fail_unlock;
> intel_encoder->new_crtc = to_intel_crtc(crtc);
> to_intel_connector(connector)->new_encoder = intel_encoder;
>
> @@ -8085,15 +8096,22 @@ bool intel_get_load_detect_pipe(struct drm_connector
> *connector,
> intel_crtc->new_config = &intel_crtc->config;
> else
> intel_crtc->new_config = NULL;
> - mutex_unlock(&crtc->mutex);
> -fail_unlock_connector:
> - mutex_unlock(&dev->mode_config.connection_mutex);
> +fail_unlock:
> + if (ret == -EDEADLK) {
> + drm_modeset_backoff(ctx);
> + goto retry;
> + }
> +
> + drm_modeset_drop_locks(ctx);
> + ww_acquire_fini(&ctx->ww_ctx);
> + drm_modeset_acquire_fini(ctx);
>
> return false;
> }
>
> void intel_release_load_detect_pipe(struct drm_connector *connector,
> - struct intel_load_detect_pipe *old)
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx)
> {
> struct intel_encoder *intel_encoder =
> intel_attached_encoder(connector);
> @@ -8117,8 +8135,7 @@ void intel_release_load_detect_pipe(struct
> drm_connector *connector,
> drm_framebuffer_unreference(old->release_fb);
> }
>
> - mutex_unlock(&crtc->mutex);
> - mutex_unlock(&connector->dev->mode_config.connection_mutex);
> + goto unlock;
> return;
> }
>
> @@ -8126,8 +8143,10 @@ void intel_release_load_detect_pipe(struct
> drm_connector *connector,
> if (old->dpms_mode != DRM_MODE_DPMS_ON)
> connector->funcs->dpms(connector, old->dpms_mode);
>
> - mutex_unlock(&crtc->mutex);
> - mutex_unlock(&connector->dev->mode_config.connection_mutex);
> +unlock:
> + drm_modeset_drop_locks(ctx);
> + ww_acquire_fini(&ctx->ww_ctx);
> + drm_modeset_acquire_fini(ctx);
> }
>
> static int i9xx_pll_refclk(struct drm_device *dev,
> @@ -11385,6 +11404,7 @@ static void intel_enable_pipe_a(struct drm_device
> *dev)
> struct intel_connector *connector;
> struct drm_connector *crt = NULL;
> struct intel_load_detect_pipe load_detect_temp;
> + struct drm_modeset_acquire_ctx ctx;
>
> /* We can't just switch on the pipe A, we need to set things up with a
> * proper mode and output configuration. As a gross hack, enable pipe A
> @@ -11401,8 +11421,8 @@ static void intel_enable_pipe_a(struct drm_device
> *dev)
> if (!crt)
> return;
>
> - if (intel_get_load_detect_pipe(crt, NULL, &load_detect_temp))
> - intel_release_load_detect_pipe(crt, &load_detect_temp);
> + if (intel_get_load_detect_pipe(crt, NULL, &load_detect_temp, &ctx))
> + intel_release_load_detect_pipe(crt, &load_detect_temp, &ctx);
>
>
> }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h
> b/drivers/gpu/drm/i915/intel_drv.h
> index d8b540b..824f8ae 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -721,9 +721,11 @@ void vlv_wait_port_ready(struct drm_i915_private
> *dev_priv,
> struct intel_digital_port *dport);
> bool intel_get_load_detect_pipe(struct drm_connector *connector,
> struct drm_display_mode *mode,
> - struct intel_load_detect_pipe *old);
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx);
> void intel_release_load_detect_pipe(struct drm_connector *connector,
> - struct intel_load_detect_pipe *old);
> + struct intel_load_detect_pipe *old,
> + struct drm_modeset_acquire_ctx *ctx);
> int intel_pin_and_fence_fb_obj(struct drm_device *dev,
> struct drm_i915_gem_object *obj,
> struct intel_ring_buffer *pipelined);
> diff --git a/drivers/gpu/drm/i915/intel_sprite.c
> b/drivers/gpu/drm/i915/intel_sprite.c
> index 213cd58..c235546 100644
> --- a/drivers/gpu/drm/i915/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/intel_sprite.c
> @@ -55,7 +55,7 @@ static bool intel_pipe_update_start(struct intel_crtc
> *crtc, uint32_t *start_vbl
> int scanline, min, max, vblank_start;
> DEFINE_WAIT(wait);
>
> - WARN_ON(!mutex_is_locked(&crtc->base.mutex));
> + WARN_ON(!drm_modeset_is_locked(&crtc->base.mutex));
>
> vblank_start = mode->crtc_vblank_start;
> if (mode->flags & DRM_MODE_FLAG_INTERLACE)
> diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> index e0193e8..97d9fc9 100644
> --- a/drivers/gpu/drm/i915/intel_tv.c
> +++ b/drivers/gpu/drm/i915/intel_tv.c
> @@ -1321,10 +1321,11 @@ intel_tv_detect(struct drm_connector *connector, bool
> force)
>
> if (force) {
> struct intel_load_detect_pipe tmp;
> + struct drm_modeset_acquire_ctx ctx;
>
> - if (intel_get_load_detect_pipe(connector, &mode, &tmp)) {
> + if (intel_get_load_detect_pipe(connector, &mode, &tmp, &ctx)) {
> type = intel_tv_detect_type(intel_tv, connector);
> - intel_release_load_detect_pipe(connector, &tmp);
> + intel_release_load_detect_pipe(connector, &tmp, &ctx);
> } else
> return connector_status_unknown;
> } else
> diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c
> b/drivers/gpu/drm/omapdrm/omap_crtc.c
> index e3c47a8..2d28dc3 100644
> --- a/drivers/gpu/drm/omapdrm/omap_crtc.c
> +++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
> @@ -319,13 +319,13 @@ static void page_flip_worker(struct work_struct *work)
> struct drm_display_mode *mode = &crtc->mode;
> struct drm_gem_object *bo;
>
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
> omap_plane_mode_set(omap_crtc->plane, crtc, crtc->primary->fb,
> 0, 0, mode->hdisplay, mode->vdisplay,
> crtc->x << 16, crtc->y << 16,
> mode->hdisplay << 16, mode->vdisplay << 16,
> vblank_cb, crtc);
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
>
> bo = omap_framebuffer_bo(crtc->primary->fb, 0);
> drm_gem_object_unreference_unlocked(bo);
> @@ -465,7 +465,7 @@ static void apply_worker(struct work_struct *work)
> * the callbacks and list modification all serialized
> * with respect to modesetting ioctls from userspace.
> */
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
> dispc_runtime_get();
>
> /*
> @@ -510,7 +510,7 @@ static void apply_worker(struct work_struct *work)
>
> out:
> dispc_runtime_put();
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
> }
>
> int omap_crtc_apply(struct drm_crtc *crtc,
> @@ -518,7 +518,7 @@ int omap_crtc_apply(struct drm_crtc *crtc,
> {
> struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
>
> - WARN_ON(!mutex_is_locked(&crtc->mutex));
> + WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
>
> /* no need to queue it again if it is already queued: */
> if (apply->queued)
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> index e7199b4..8f3edc4 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
> @@ -187,7 +187,7 @@ int vmw_du_crtc_cursor_set(struct drm_crtc *crtc, struct
> drm_file *file_priv,
> * can do this since the caller in the drm core doesn't check anything
> * which is protected by any looks.
> */
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
> drm_modeset_lock_all(dev_priv->dev);
>
> /* A lot of the code assumes this */
> @@ -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);
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
>
> return ret;
> }
> @@ -273,7 +273,7 @@ int vmw_du_crtc_cursor_move(struct drm_crtc *crtc, int x,
> int y)
> * can do this since the caller in the drm core doesn't check anything
> * which is protected by any looks.
> */
> - mutex_unlock(&crtc->mutex);
> + drm_modeset_unlock(&crtc->mutex);
> drm_modeset_lock_all(dev_priv->dev);
>
> vmw_cursor_update_position(dev_priv, shown,
> @@ -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);
> - mutex_lock(&crtc->mutex);
> + drm_modeset_lock(&crtc->mutex, NULL);
>
> return 0;
> }
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index 12f10bc..a9b8a5d 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -1184,11 +1184,6 @@ static inline int drm_device_is_unplugged(struct
> drm_device *dev)
> return ret;
> }
>
> -static inline bool drm_modeset_is_locked(struct drm_device *dev)
> -{
> - return mutex_is_locked(&dev->mode_config.mutex);
> -}
> -
> static inline bool drm_is_render_client(const struct drm_file *file_priv)
> {
> return file_priv->minor->type == DRM_MINOR_RENDER;
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 1bd6708..deadb32 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -33,6 +33,7 @@
> #include <linux/hdmi.h>
> #include <drm/drm_mode.h>
> #include <drm/drm_fourcc.h>
> +#include <drm/drm_modeset_lock.h>
>
> struct drm_device;
> struct drm_mode_set;
> @@ -205,6 +206,10 @@ struct drm_property {
> struct list_head enum_blob_list;
> };
>
> +void drm_modeset_lock_all(struct drm_device *dev);
> +void drm_modeset_unlock_all(struct drm_device *dev);
> +void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
> +
> struct drm_crtc;
> struct drm_connector;
> struct drm_encoder;
> @@ -280,6 +285,7 @@ struct drm_crtc_funcs {
> * drm_crtc - central CRTC control structure
> * @dev: parent DRM device
> * @head: list management
> + * @mutex: per-CRTC locking
> * @base: base KMS object for ID tracking etc.
> * @primary: primary plane for this CRTC
> * @cursor: cursor plane for this CRTC
> @@ -314,7 +320,7 @@ struct drm_crtc {
> * state, ...) and a write lock for everything which can be update
> * without a full modeset (fb, cursor data, ...)
> */
> - struct mutex mutex;
> + struct drm_modeset_lock mutex;
>
> struct drm_mode_object base;
>
> @@ -738,7 +744,8 @@ struct drm_mode_group {
> */
> struct drm_mode_config {
> struct mutex mutex; /* protects configuration (mode lists etc.) */
> - struct mutex connection_mutex; /* protects connector->encoder and
> encoder->crtc links */
> + struct drm_modeset_lock connection_mutex; /* protects
> connector->encoder and encoder->crtc links */
> + struct drm_modeset_acquire_ctx *acquire_ctx; /* for legacy _lock_all()
> / _unlock_all() */
> struct mutex idr_mutex; /* for IDR management */
> struct idr crtc_idr; /* use this idr for all IDs, fb, crtc, connector,
> modes - just makes life easier */
> /* this is limited to one for now */
> @@ -839,10 +846,6 @@ struct drm_prop_enum_list {
> char *name;
> };
>
> -extern void drm_modeset_lock_all(struct drm_device *dev);
> -extern void drm_modeset_unlock_all(struct drm_device *dev);
> -extern void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
> -
> extern int drm_crtc_init_with_planes(struct drm_device *dev,
> struct drm_crtc *crtc,
> struct drm_plane *primary,
> diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
> new file mode 100644
> index 0000000..2630da3
> --- /dev/null
> +++ b/include/drm/drm_modeset_lock.h
> @@ -0,0 +1,139 @@
> +/*
> + * Copyright (C) 2014 Red Hat
> + * Author: Rob Clark <robdclark at gmail.com>
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
> + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> + * OTHER DEALINGS IN THE SOFTWARE.
> + */
> +
> +#ifndef DRM_MODESET_LOCK_H_
> +#define DRM_MODESET_LOCK_H_
> +
> +#include <linux/ww_mutex.h>
> +
> +struct drm_modeset_lock;
> +
> +struct drm_modeset_acquire_ctx {
> +
> + struct ww_acquire_ctx ww_ctx;
> +
> + bool nolock : 1;
> + bool nonblock : 1;
> +
> + /* just for debugging, the context is 'frozen' in drm_atomic_check()
> + * to catch anyone who might be trying to acquire a lock after it is
> + * too late.
> + */
> + bool frozen : 1;
> +
> + /* contended lock: if a lock is contended you should only call
> + * drm_modeset_backoff() which drops locks and slow-locks the
> + * contended lock.
> + */
> + struct drm_modeset_lock *contended;
> +
> + /* list of 'struct drm_modeset_lock': */
> + struct list_head locked;
> +
> + /* currently simply for protecting against 'locked' list manipulation
> + * between original thread calling atomic->end() and driver thread
> + * calling back drm_atomic_commit_unlocked().
> + *
> + * Other spots are sufficiently synchronized by virtue of holding
> + * the lock's ww_mutex. But during the lock/resource hand-over to the
> + * driver thread (drop_locks()/grab_locks()), we cannot rely on this.
> + */
> + struct mutex mutex;
> +};
> +
> +/**
> + * drm_modeset_lock - used for locking modeset resources.
> + * @mutex: resource locking
> + * @atomic_pending: is this resource part of a still-pending
> + * atomic update
> + * @head: used to hold it's place on state->locked list when
> + * part of an atomic update
> + *
> + * Used for locking CRTCs and other modeset resources.
> + */
> +struct drm_modeset_lock {
> + /**
> + * modeset lock
> + */
> + struct ww_mutex mutex;
> +
> + /**
> + * Are we busy (pending asynchronous/NONBLOCK update)? Any further
> + * asynchronous update will return -EBUSY if it also needs to acquire
> + * this lock. While a synchronous update will block until the pending
> + * async update completes.
> + *
> + * Drivers must ensure the update is completed before sending vblank
> + * event to userspace. Typically this just means don't send event
> + * before drm_atomic_commit_unlocked() returns.
> + */
> + bool atomic_pending;
> +
> + /**
> + * Resources that are locked as part of an atomic update are added
> + * to a list (so we know what to unlock at the end).
> + */
> + struct list_head head;
> +
> + /**
> + * For waiting on atomic_pending locks, if not a NONBLOCK operation.
> + */
> + wait_queue_head_t event;
> +};
> +
> +extern struct ww_class crtc_ww_class;
> +
> +void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
> + bool nolock, bool nonblock);
> +void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
> +void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
> +void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
> +
> +static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
> +{
> + ww_mutex_init(&lock->mutex, &crtc_ww_class);
> + INIT_LIST_HEAD(&lock->head);
> + init_waitqueue_head(&lock->event);
> +}
> +
> +static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
> +{
> + WARN_ON(!list_empty(&lock->head));
> +}
> +
> +static inline bool drm_modeset_is_locked(struct drm_modeset_lock *lock)
> +{
> + return ww_mutex_is_locked(&lock->mutex);
> +}
> +
> +int drm_modeset_lock(struct drm_modeset_lock *lock,
> + struct drm_modeset_acquire_ctx *ctx);
> +int drm_modeset_lock_interruptible(struct drm_modeset_lock *lock,
> + struct drm_modeset_acquire_ctx *ctx);
> +void drm_modeset_unlock(struct drm_modeset_lock *lock);
> +
> +struct drm_device;
> +int drm_modeset_lock_all_crtcs(struct drm_device *dev,
> + struct drm_modeset_acquire_ctx *ctx);
> +
> +#endif /* DRM_MODESET_LOCK_H_ */
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index ded505e..6421edc 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -511,4 +511,7 @@ struct drm_mode_destroy_dumb {
> uint32_t handle;
> };
>
> +#define DRM_MODE_ATOMIC_NONBLOCK 0x0200
> +#define DRM_MODE_ATOMIC_NOLOCK 0x8000 /* only used internally */
> +
> #endif
> --
> 1.9.3
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
