On Thu, Dec 10, 2020 at 08:02:31AM +0000, Chris Wilson wrote:
> The free_list and worker was introduced in commit 5f09a9c8ab6b ("drm/i915:
> Allow contexts to be unreferenced locklessly"), but subsequently made
> redundant by the removal of the last sleeping lock in commit 2935ed5339c4
> ("drm/i915: Remove logical HW ID"). As we can now free the GEM context
> immediately from any context, remove the deferral of the free_list
>
> v2: Lift removing the context from the global list into close().
>
> Suggested-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/gem/i915_gem_context.c | 59 +++----------------
> drivers/gpu/drm/i915/gem/i915_gem_context.h | 1 -
> .../gpu/drm/i915/gem/i915_gem_context_types.h | 1 -
> drivers/gpu/drm/i915/i915_drv.h | 3 -
> drivers/gpu/drm/i915/i915_gem.c | 2 -
> .../gpu/drm/i915/selftests/mock_gem_device.c | 2 -
> 6 files changed, 8 insertions(+), 60 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> index ad136d009d9b..738a07b3583c 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> @@ -334,13 +334,12 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx)
> return e;
> }
>
> -static void i915_gem_context_free(struct i915_gem_context *ctx)
> +void i915_gem_context_release(struct kref *ref)
> {
> - GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
> + struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref);
>
> - spin_lock(&ctx->i915->gem.contexts.lock);
> - list_del(&ctx->link);
> - spin_unlock(&ctx->i915->gem.contexts.lock);
> + trace_i915_context_free(ctx);
> + GEM_BUG_ON(!i915_gem_context_is_closed(ctx));
>
> mutex_destroy(&ctx->engines_mutex);
> mutex_destroy(&ctx->lut_mutex);
> @@ -354,37 +353,6 @@ static void i915_gem_context_free(struct i915_gem_context *ctx)
> kfree_rcu(ctx, rcu);
> }
>
> -static void contexts_free_all(struct llist_node *list)
> -{
> - struct i915_gem_context *ctx, *cn;
> -
> - llist_for_each_entry_safe(ctx, cn, list, free_link)
> - i915_gem_context_free(ctx);
> -}
> -
> -static void contexts_flush_free(struct i915_gem_contexts *gc)
> -{
> - contexts_free_all(llist_del_all(&gc->free_list));
> -}
> -
> -static void contexts_free_worker(struct work_struct *work)
> -{
> - struct i915_gem_contexts *gc =
> - container_of(work, typeof(*gc), free_work);
> -
> - contexts_flush_free(gc);
> -}
> -
> -void i915_gem_context_release(struct kref *ref)
> -{
> - struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref);
> - struct i915_gem_contexts *gc = &ctx->i915->gem.contexts;
> -
> - trace_i915_context_free(ctx);
> - if (llist_add(&ctx->free_link, &gc->free_list))
> - schedule_work(&gc->free_work);
> -}
> -
> static inline struct i915_gem_engines *
> __context_engines_static(const struct i915_gem_context *ctx)
> {
> @@ -633,6 +601,10 @@ static void context_close(struct i915_gem_context *ctx)
> */
> lut_close(ctx);
>
> + spin_lock(&ctx->i915->gem.contexts.lock);
> + list_del(&ctx->link);
> + spin_unlock(&ctx->i915->gem.contexts.lock);
> +
> mutex_unlock(&ctx->mutex);
>
> /*
> @@ -850,9 +822,6 @@ i915_gem_create_context(struct drm_i915_private *i915, unsigned int flags)
> !HAS_EXECLISTS(i915))
> return ERR_PTR(-EINVAL);
>
> - /* Reap the stale contexts */
> - contexts_flush_free(&i915->gem.contexts);
> -
> ctx = __create_context(i915);
> if (IS_ERR(ctx))
> return ctx;
> @@ -897,9 +866,6 @@ static void init_contexts(struct i915_gem_contexts *gc)
> {
> spin_lock_init(&gc->lock);
> INIT_LIST_HEAD(&gc->list);
> -
> - INIT_WORK(&gc->free_work, contexts_free_worker);
> - init_llist_head(&gc->free_list);
> }
>
> void i915_gem_init__contexts(struct drm_i915_private *i915)
> @@ -907,12 +873,6 @@ void i915_gem_init__contexts(struct drm_i915_private *i915)
> init_contexts(&i915->gem.contexts);
> }
>
> -void i915_gem_driver_release__contexts(struct drm_i915_private *i915)
> -{
> - flush_work(&i915->gem.contexts.free_work);
> - rcu_barrier(); /* and flush the left over RCU frees */
> -}
> -
> static int gem_context_register(struct i915_gem_context *ctx,
> struct drm_i915_file_private *fpriv,
> u32 *id)
> @@ -986,7 +946,6 @@ int i915_gem_context_open(struct drm_i915_private *i915,
> void i915_gem_context_close(struct drm_file *file)
> {
> struct drm_i915_file_private *file_priv = file->driver_priv;
> - struct drm_i915_private *i915 = file_priv->dev_priv;
> struct i915_address_space *vm;
> struct i915_gem_context *ctx;
> unsigned long idx;
> @@ -998,8 +957,6 @@ void i915_gem_context_close(struct drm_file *file)
> xa_for_each(&file_priv->vm_xa, idx, vm)
> i915_vm_put(vm);
> xa_destroy(&file_priv->vm_xa);
> -
> - contexts_flush_free(&i915->gem.contexts);
> }
>
> int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h b/drivers/gpu/drm/i915/gem/i915_gem_context.h
> index a133f92bbedb..b5c908f3f4f2 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h
> @@ -110,7 +110,6 @@ i915_gem_context_clear_user_engines(struct i915_gem_context *ctx)
>
> /* i915_gem_context.c */
> void i915_gem_init__contexts(struct drm_i915_private *i915);
> -void i915_gem_driver_release__contexts(struct drm_i915_private *i915);
>
> int i915_gem_context_open(struct drm_i915_private *i915,
> struct drm_file *file);
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> index ae14ca24a11f..1449f54924e0 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context_types.h
> @@ -108,7 +108,6 @@ struct i915_gem_context {
>
> /** link: place with &drm_i915_private.context_list */
> struct list_head link;
> - struct llist_node free_link;
>
> /**
> * @ref: reference count
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 5d04b282c060..c2d0156e8a5d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1172,9 +1172,6 @@ struct drm_i915_private {
> struct i915_gem_contexts {
> spinlock_t lock; /* locks list */
> struct list_head list;
> -
> - struct llist_head free_list;
> - struct work_struct free_work;
> } contexts;
>
> /*
> diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
> index 58276694c848..17a4636ee542 100644
> --- a/drivers/gpu/drm/i915/i915_gem.c
> +++ b/drivers/gpu/drm/i915/i915_gem.c
> @@ -1207,8 +1207,6 @@ void i915_gem_driver_remove(struct drm_i915_private *dev_priv)
>
> void i915_gem_driver_release(struct drm_i915_private *dev_priv)
> {
> - i915_gem_driver_release__contexts(dev_priv);
> -
> intel_gt_driver_release(&dev_priv->gt);
>
> intel_wa_list_free(&dev_priv->gt_wa_list);
> diff --git a/drivers/gpu/drm/i915/selftests/mock_gem_device.c b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
> index e946bd2087d8..0188f877cab2 100644
> --- a/drivers/gpu/drm/i915/selftests/mock_gem_device.c
> +++ b/drivers/gpu/drm/i915/selftests/mock_gem_device.c
> @@ -64,8 +64,6 @@ static void mock_device_release(struct drm_device *dev)
> mock_device_flush(i915);
> intel_gt_driver_remove(&i915->gt);
>
> - i915_gem_driver_release__contexts(i915);
> -
> i915_gem_drain_workqueue(i915);
> i915_gem_drain_freed_objects(i915);
>
> --
> 2.20.1
>
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