drm/i915: Keep a list of all contexts

I have implemented this patch before without creating a separate list
(I'm having trouble finding the links, but the messages ids are:
<1364942743-6041-2-git-send-email-ben@bwidawsk.net>
<1365118914-15753-9-git-send-email-ben@bwidawsk.net>)

However, the code is much simpler to just use a list and it makes the
code from the next patch a lot more pretty.

As you'll see in the next patch, the reason for this is to be able to
specify when a context needs to get L3 remapping. More details there.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1442,6 +1442,7 @@ static int i915_context_status(struct seq_file *m, void *unused)
 	struct drm_device *dev = node->minor->dev;
 	drm_i915_private_t *dev_priv = dev->dev_private;
 	struct intel_ring_buffer *ring;
+	struct i915_hw_context *ctx;
 	int ret, i;
 
 	ret = mutex_lock_interruptible(&dev->mode_config.mutex);
@@ -1460,12 +1461,14 @@ static int i915_context_status(struct seq_file *m, void *unused)
 		seq_putc(m, '\n');
 	}
 
-	for_each_ring(ring, dev_priv, i) {
-		if (ring->default_context) {
-			seq_printf(m, "HW default context %s ", ring->name);
-			describe_obj(m, ring->default_context->obj);
-			seq_putc(m, '\n');
-		}
+	list_for_each_entry(ctx, &dev_priv->context_list, link) {
+		seq_puts(m, "HW context ");
+		for_each_ring(ring, dev_priv, i)
+			if (ring->default_context == ctx)
+				seq_printf(m, "(default context %s) ", ring->name);
+
+		describe_obj(m, ctx->obj);
+		seq_putc(m, '\n');
 	}
 
 	mutex_unlock(&dev->mode_config.mutex);

drivers/gpu/drm/i915/i915_drv.h

@@ -605,6 +605,8 @@ struct i915_hw_context {
 	struct intel_ring_buffer *ring;
 	struct drm_i915_gem_object *obj;
 	struct i915_ctx_hang_stats hang_stats;
+
+	struct list_head link;
 };
 
 struct i915_fbc {
@@ -1343,6 +1345,7 @@ typedef struct drm_i915_private {
 
 	bool hw_contexts_disabled;
 	uint32_t hw_context_size;
+	struct list_head context_list;
 
 	u32 fdi_rx_config;
 

drivers/gpu/drm/i915/i915_gem.c

@@ -4541,6 +4541,7 @@ i915_gem_load(struct drm_device *dev)
 	INIT_LIST_HEAD(&dev_priv->vm_list);
 	i915_init_vm(dev_priv, &dev_priv->gtt.base);
 
+	INIT_LIST_HEAD(&dev_priv->context_list);
 	INIT_LIST_HEAD(&dev_priv->mm.unbound_list);
 	INIT_LIST_HEAD(&dev_priv->mm.bound_list);
 	INIT_LIST_HEAD(&dev_priv->mm.fence_list);

drivers/gpu/drm/i915/i915_gem_context.c

@@ -129,6 +129,7 @@ void i915_gem_context_free(struct kref *ctx_ref)
 	struct i915_hw_context *ctx = container_of(ctx_ref,
 						   typeof(*ctx), ref);
 
+	list_del(&ctx->link);
 	drm_gem_object_unreference(&ctx->obj->base);
 	kfree(ctx);
 }
@@ -147,6 +148,7 @@ create_hw_context(struct drm_device *dev,
 
 	kref_init(&ctx->ref);
 	ctx->obj = i915_gem_alloc_object(dev, dev_priv->hw_context_size);
+	INIT_LIST_HEAD(&ctx->link);
 	if (ctx->obj == NULL) {
 		kfree(ctx);
 		DRM_DEBUG_DRIVER("Context object allocated failed\n");
@@ -166,6 +168,7 @@ create_hw_context(struct drm_device *dev,
 	 * assertion in the context switch code.
 	 */
 	ctx->ring = &dev_priv->ring[RCS];
+	list_add_tail(&ctx->link, &dev_priv->context_list);
 
 	/* Default context will never have a file_priv */
 	if (file_priv == NULL)