[RFC 3/6] drm/i915: Expose list of clients in sysfs

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Expose a list of clients with open file handles in sysfs.

This will be a basis for a top-like utility showing per-client and per-
engine GPU load.

Currently we only expose each client's pid and name under opaque numbered
directories in /sys/class/drm/card0/clients/.

For instance:

/sys/class/drm/card0/clients/3/name: Xorg
/sys/class/drm/card0/clients/3/pid: 5664

v2:
 Chris Wilson:
 * Enclose new members into dedicated structs.
 * Protect against failed sysfs registration.

v3:
 * sysfs_attr_init.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h   |  19 +++++
 drivers/gpu/drm/i915/i915_gem.c   | 121 ++++++++++++++++++++++++++++--
 drivers/gpu/drm/i915/i915_sysfs.c |   8 ++
 3 files changed, 140 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d0257808734c..1d7a94555a87 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -242,6 +242,20 @@ struct drm_i915_file_private {
 	/** ban_score: Accumulated score of all ctx bans and fast hangs. */
 	atomic_t ban_score;
 	unsigned long hang_timestamp;
+
+	struct i915_drm_client {
+		unsigned int id;
+
+		pid_t pid;
+		char *name;
+
+		struct kobject *root;
+
+		struct {
+			struct device_attribute pid;
+			struct device_attribute name;
+		} attr;
+	} client;
 };
 
 /* Interface history:
@@ -2057,6 +2071,11 @@ struct drm_i915_private {
 
 	struct i915_pmu pmu;
 
+	struct i915_drm_clients {
+		struct kobject *root;
+		atomic_t serial;
+	} clients;
+
 	struct i915_hdcp_comp_master *hdcp_master;
 	bool hdcp_comp_added;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 2fcec1bfb038..0ae5764a58d2 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4814,6 +4814,96 @@ int i915_gem_freeze_late(struct drm_i915_private *i915)
 	return 0;
 }
 
+static ssize_t
+show_client_name(struct device *kdev, struct device_attribute *attr, char *buf)
+{
+	struct drm_i915_file_private *file_priv =
+		container_of(attr, struct drm_i915_file_private,
+			     client.attr.name);
+
+	return snprintf(buf, PAGE_SIZE, "%s", file_priv->client.name);
+}
+
+static ssize_t
+show_client_pid(struct device *kdev, struct device_attribute *attr, char *buf)
+{
+	struct drm_i915_file_private *file_priv =
+		container_of(attr, struct drm_i915_file_private,
+			     client.attr.pid);
+
+	return snprintf(buf, PAGE_SIZE, "%u", file_priv->client.pid);
+}
+
+static int
+i915_gem_add_client(struct drm_i915_private *i915,
+		struct drm_i915_file_private *file_priv,
+		struct task_struct *task,
+		unsigned int serial)
+{
+	int ret = -ENOMEM;
+	struct device_attribute *attr;
+	char id[32];
+
+	if (!i915->clients.root)
+		goto err_name;
+
+	file_priv->client.name = kstrdup(task->comm, GFP_KERNEL);
+	if (!file_priv->client.name)
+		goto err_name;
+
+	snprintf(id, sizeof(id), "%u", serial);
+	file_priv->client.root = kobject_create_and_add(id,
+							i915->clients.root);
+	if (!file_priv->client.root)
+		goto err_client;
+
+	attr = &file_priv->client.attr.name;
+	sysfs_attr_init(&attr->attr);
+	attr->attr.name = "name";
+	attr->attr.mode = 0444;
+	attr->show = show_client_name;
+
+	ret = sysfs_create_file(file_priv->client.root,
+				(struct attribute *)attr);
+	if (ret)
+		goto err_attr_name;
+
+	attr = &file_priv->client.attr.pid;
+	sysfs_attr_init(&attr->attr);
+	attr->attr.name = "pid";
+	attr->attr.mode = 0444;
+	attr->show = show_client_pid;
+
+	ret = sysfs_create_file(file_priv->client.root,
+				(struct attribute *)attr);
+	if (ret)
+		goto err_attr_pid;
+
+	file_priv->client.pid = pid_nr(get_task_pid(task, PIDTYPE_PID));
+
+	return 0;
+
+err_attr_pid:
+	sysfs_remove_file(file_priv->client.root,
+			  (struct attribute *)&file_priv->client.attr.name);
+err_attr_name:
+	kobject_put(file_priv->client.root);
+err_client:
+	kfree(file_priv->client.name);
+err_name:
+	return ret;
+}
+
+static void i915_gem_remove_client(struct drm_i915_file_private *file_priv)
+{
+	sysfs_remove_file(file_priv->client.root,
+			  (struct attribute *)&file_priv->client.attr.pid);
+	sysfs_remove_file(file_priv->client.root,
+			  (struct attribute *)&file_priv->client.attr.name);
+	kobject_put(file_priv->client.root);
+	kfree(file_priv->client.name);
+}
+
 void i915_gem_release(struct drm_device *dev, struct drm_file *file)
 {
 	struct drm_i915_file_private *file_priv = file->driver_priv;
@@ -4827,33 +4917,48 @@ void i915_gem_release(struct drm_device *dev, struct drm_file *file)
 	list_for_each_entry(request, &file_priv->mm.request_list, client_link)
 		request->file_priv = NULL;
 	spin_unlock(&file_priv->mm.lock);
+
+	i915_gem_remove_client(file_priv);
 }
 
 int i915_gem_open(struct drm_i915_private *i915, struct drm_file *file)
 {
+	int ret = -ENOMEM;
 	struct drm_i915_file_private *file_priv;
-	int ret;
 
 	DRM_DEBUG("\n");
 
 	file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
 	if (!file_priv)
-		return -ENOMEM;
+		goto err_alloc;
+
+	file_priv->client.id = atomic_inc_return(&i915->clients.serial);
+	ret = i915_gem_add_client(i915, file_priv, current,
+				  file_priv->client.id);
+	if (ret)
+		goto err_client;
 
 	file->driver_priv = file_priv;
+	ret = i915_gem_context_open(i915, file);
+	if (ret)
+		goto err_context;
+
 	file_priv->dev_priv = i915;
 	file_priv->file = file;
+	file_priv->bsd_engine = -1;
+	file_priv->hang_timestamp = jiffies;
 
 	spin_lock_init(&file_priv->mm.lock);
 	INIT_LIST_HEAD(&file_priv->mm.request_list);
 
-	file_priv->bsd_engine = -1;
-	file_priv->hang_timestamp = jiffies;
-
-	ret = i915_gem_context_open(i915, file);
-	if (ret)
-		kfree(file_priv);
+	return 0;
 
+err_context:
+	i915_gem_remove_client(file_priv);
+err_client:
+	atomic_dec(&i915->clients.serial);
+	kfree(file_priv);
+err_alloc:
 	return ret;
 }
 
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index 3ef07b987d40..06a558436f54 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -576,6 +576,11 @@ void i915_setup_sysfs(struct drm_i915_private *dev_priv)
 	struct device *kdev = dev_priv->drm.primary->kdev;
 	int ret;
 
+	dev_priv->clients.root =
+		kobject_create_and_add("clients", &kdev->kobj);
+	if (!dev_priv->clients.root)
+		DRM_ERROR("Per-client sysfs setup failed\n");
+
 #ifdef CONFIG_PM
 	if (HAS_RC6(dev_priv)) {
 		ret = sysfs_merge_group(&kdev->kobj,
@@ -636,4 +641,7 @@ void i915_teardown_sysfs(struct drm_i915_private *dev_priv)
 	sysfs_unmerge_group(&kdev->kobj, &rc6_attr_group);
 	sysfs_unmerge_group(&kdev->kobj, &rc6p_attr_group);
 #endif
+
+	if (dev_priv->clients.root)
+		kobject_put(dev_priv->clients.root);
 }
-- 
2.19.1

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