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Commit 5f09a9c8 authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915: Allow contexts to be unreferenced locklessly 



If we move the actual cleanup of the context to a worker, we can allow
the final free to be called from any context and avoid undue latency in
the caller.

v2: Negotiate handling the delayed contexts free by flushing the
workqueue before calling i915_gem_context_fini() and performing the final
free of the kernel context directly
v3: Flush deferred frees before new context allocations

Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620110547.15947-2-chris@chris-wilson.co.uk
parent 829a0af2

drivers/gpu/drm/i915/gvt/scheduler.c

+1 −1
Original line number Diff line number Diff line
@@ -620,7 +620,7 @@ int intel_gvt_init_workload_scheduler(struct intel_gvt *gvt) 


void intel_vgpu_clean_gvt_context(struct intel_vgpu *vgpu)

{

	i915_gem_context_put_unlocked(vgpu->shadow_ctx);

	i915_gem_context_put(vgpu->shadow_ctx);

}



int intel_vgpu_init_gvt_context(struct intel_vgpu *vgpu)

drivers/gpu/drm/i915/i915_drv.c

+2 −0
Original line number Diff line number Diff line
@@ -585,6 +585,8 @@ static const struct vga_switcheroo_client_ops i915_switcheroo_ops = { 


static void i915_gem_fini(struct drm_i915_private *dev_priv)

{

	flush_workqueue(dev_priv->wq);



	mutex_lock(&dev_priv->drm.struct_mutex);

	intel_uc_fini_hw(dev_priv);

	i915_gem_cleanup_engines(dev_priv);

drivers/gpu/drm/i915/i915_drv.h

+2 −21
Original line number Diff line number Diff line
@@ -2315,6 +2315,8 @@ struct drm_i915_private { 


	struct {

		struct list_head list;

		struct llist_head free_list;

		struct work_struct free_work;



		/* The hw wants to have a stable context identifier for the

		 * lifetime of the context (for OA, PASID, faults, etc).
@@ -3545,27 +3547,6 @@ i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32 id) 
	return ctx;

}



static inline struct i915_gem_context *

i915_gem_context_get(struct i915_gem_context *ctx)

{

	kref_get(&ctx->ref);

	return ctx;

}



static inline void i915_gem_context_put(struct i915_gem_context *ctx)

{

	lockdep_assert_held(&ctx->i915->drm.struct_mutex);

	kref_put(&ctx->ref, i915_gem_context_free);

}



static inline void i915_gem_context_put_unlocked(struct i915_gem_context *ctx)

{

	struct mutex *lock = &ctx->i915->drm.struct_mutex;



	if (kref_put_mutex(&ctx->ref, i915_gem_context_free, lock))

		mutex_unlock(lock);

}



static inline struct intel_timeline *

i915_gem_context_lookup_timeline(struct i915_gem_context *ctx,

				 struct intel_engine_cs *engine)

drivers/gpu/drm/i915/i915_gem_context.c

+48 −11
Original line number Diff line number Diff line
@@ -158,13 +158,11 @@ static void vma_lut_free(struct i915_gem_context *ctx) 
	kvfree(lut->ht);

}



void i915_gem_context_free(struct kref *ctx_ref)

static void i915_gem_context_free(struct i915_gem_context *ctx)

{

	struct i915_gem_context *ctx = container_of(ctx_ref, typeof(*ctx), ref);

	int i;



	lockdep_assert_held(&ctx->i915->drm.struct_mutex);

	trace_i915_context_free(ctx);

	GEM_BUG_ON(!i915_gem_context_is_closed(ctx));



	vma_lut_free(ctx);
@@ -192,6 +190,37 @@ void i915_gem_context_free(struct kref *ctx_ref) 
	kfree(ctx);

}



static void contexts_free(struct drm_i915_private *i915)

{

	struct llist_node *freed = llist_del_all(&i915->contexts.free_list);

	struct i915_gem_context *ctx;



	lockdep_assert_held(&i915->drm.struct_mutex);



	llist_for_each_entry(ctx, freed, free_link)

		i915_gem_context_free(ctx);

}



static void contexts_free_worker(struct work_struct *work)

{

	struct drm_i915_private *i915 =

		container_of(work, typeof(*i915), contexts.free_work);



	mutex_lock(&i915->drm.struct_mutex);

	contexts_free(i915);

	mutex_unlock(&i915->drm.struct_mutex);

}



void i915_gem_context_release(struct kref *ref)

{

	struct i915_gem_context *ctx = container_of(ref, typeof(*ctx), ref);

	struct drm_i915_private *i915 = ctx->i915;



	trace_i915_context_free(ctx);

	if (llist_add(&ctx->free_link, &i915->contexts.free_list))

		queue_work(i915->wq, &i915->contexts.free_work);

}



static void context_close(struct i915_gem_context *ctx)

{

	i915_gem_context_set_closed(ctx);
@@ -428,6 +457,8 @@ int i915_gem_contexts_init(struct drm_i915_private *dev_priv) 
		return 0;



	INIT_LIST_HEAD(&dev_priv->contexts.list);

	INIT_WORK(&dev_priv->contexts.free_work, contexts_free_worker);

	init_llist_head(&dev_priv->contexts.free_list);



	if (intel_vgpu_active(dev_priv) &&

	    HAS_LOGICAL_RING_CONTEXTS(dev_priv)) {
@@ -505,18 +536,20 @@ void i915_gem_contexts_lost(struct drm_i915_private *dev_priv) 
	}

}



void i915_gem_contexts_fini(struct drm_i915_private *dev_priv)

void i915_gem_contexts_fini(struct drm_i915_private *i915)

{

	struct i915_gem_context *dctx = dev_priv->kernel_context;



	lockdep_assert_held(&dev_priv->drm.struct_mutex);

	struct i915_gem_context *ctx;



	GEM_BUG_ON(!i915_gem_context_is_kernel(dctx));

	lockdep_assert_held(&i915->drm.struct_mutex);



	context_close(dctx);

	dev_priv->kernel_context = NULL;

	/* Keep the context so that we can free it immediately ourselves */

	ctx = i915_gem_context_get(fetch_and_zero(&i915->kernel_context));

	GEM_BUG_ON(!i915_gem_context_is_kernel(ctx));

	context_close(ctx);

	i915_gem_context_free(ctx);



	ida_destroy(&dev_priv->contexts.hw_ida);

	/* Must free all deferred contexts (via flush_workqueue) first */

	ida_destroy(&i915->contexts.hw_ida);

}



static int context_idr_cleanup(int id, void *p, void *data)
@@ -957,6 +990,10 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data, 
	if (ret)

		return ret;



	/* Reap stale contexts */

	i915_gem_retire_requests(dev_priv);

	contexts_free(dev_priv);



	ctx = i915_gem_create_context(dev_priv, file_priv);

	mutex_unlock(&dev->struct_mutex);

	if (IS_ERR(ctx))

drivers/gpu/drm/i915/i915_gem_context.h

+14 −1
Original line number Diff line number Diff line
@@ -86,6 +86,7 @@ struct i915_gem_context { 


	/** link: place with &drm_i915_private.context_list */

	struct list_head link;

	struct llist_node free_link;



	/**

	 * @ref: reference count
@@ -284,7 +285,7 @@ void i915_gem_context_close(struct drm_file *file); 
int i915_switch_context(struct drm_i915_gem_request *req);

int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv);



void i915_gem_context_free(struct kref *ctx_ref);

void i915_gem_context_release(struct kref *ctx_ref);

struct i915_gem_context *

i915_gem_context_create_gvt(struct drm_device *dev);
@@ -299,4 +300,16 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data, 
int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void *data,

				       struct drm_file *file);



static inline struct i915_gem_context *

i915_gem_context_get(struct i915_gem_context *ctx)

{

	kref_get(&ctx->ref);

	return ctx;

}



static inline void i915_gem_context_put(struct i915_gem_context *ctx)

{

	kref_put(&ctx->ref, i915_gem_context_release);

}



#endif /* !__I915_GEM_CONTEXT_H__ */