[RFC PATCH v2 2/5] cgroup: Add mechanism to register DRM devices

[Kenny Ho <Kenny.Ho-5C7GfCeVMHo@public.gmane.org>]

Change-Id: I908ee6975ea0585e4c30eafde4599f87094d8c65
Signed-off-by: Kenny Ho <Kenny.Ho@amd.com>
---
 include/drm/drm_cgroup.h   |  24 ++++++++
 include/linux/cgroup_drm.h |  10 ++++
 kernel/cgroup/drm.c        | 118 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 151 insertions(+), 1 deletion(-)
 create mode 100644 include/drm/drm_cgroup.h

diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
new file mode 100644
index 000000000000..ddb9eab64360
--- /dev/null
+++ b/include/drm/drm_cgroup.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: MIT
+ * Copyright 2019 Advanced Micro Devices, Inc.
+ */
+#ifndef __DRM_CGROUP_H__
+#define __DRM_CGROUP_H__
+
+#ifdef CONFIG_CGROUP_DRM
+
+int drmcgrp_register_device(struct drm_device *device);
+
+int drmcgrp_unregister_device(struct drm_device *device);
+
+#else
+static inline int drmcgrp_register_device(struct drm_device *device)
+{
+	return 0;
+}
+
+static inline int drmcgrp_unregister_device(struct drm_device *device)
+{
+	return 0;
+}
+#endif /* CONFIG_CGROUP_DRM */
+#endif /* __DRM_CGROUP_H__ */
diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
index 121001be1230..d7ccf434ca6b 100644
--- a/include/linux/cgroup_drm.h
+++ b/include/linux/cgroup_drm.h
@@ -6,10 +6,20 @@
 
 #ifdef CONFIG_CGROUP_DRM
 
+#include <linux/mutex.h>
 #include <linux/cgroup.h>
+#include <drm/drm_file.h>
+
+/* limit defined per the way drm_minor_alloc operates */
+#define MAX_DRM_DEV (64 * DRM_MINOR_RENDER)
+
+struct drmcgrp_device_resource {
+	/* for per device stats */
+};
 
 struct drmcgrp {
 	struct cgroup_subsys_state	css;
+	struct drmcgrp_device_resource	*dev_resources[MAX_DRM_DEV];
 };
 
 static inline struct drmcgrp *css_drmcgrp(struct cgroup_subsys_state *css)
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index 620c887d6d24..f9ef4bf042d8 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -1,16 +1,79 @@
 // SPDX-License-Identifier: MIT
 // Copyright 2019 Advanced Micro Devices, Inc.
+#include <linux/export.h>
 #include <linux/slab.h>
 #include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/seq_file.h>
+#include <linux/mutex.h>
 #include <linux/cgroup_drm.h>
+#include <drm/drm_device.h>
+#include <drm/drm_cgroup.h>
+
+static DEFINE_MUTEX(drmcgrp_mutex);
+
+struct drmcgrp_device {
+	struct drm_device	*dev;
+	struct mutex		mutex;
+};
+
+/* indexed by drm_minor for access speed */
+static struct drmcgrp_device	*known_drmcgrp_devs[MAX_DRM_DEV];
+
+static int max_minor;
+
 
 static struct drmcgrp *root_drmcgrp __read_mostly;
 
 static void drmcgrp_css_free(struct cgroup_subsys_state *css)
 {
 	struct drmcgrp *drmcgrp = css_drmcgrp(css);
+	int i;
+
+	for (i = 0; i <= max_minor; i++) {
+		if (drmcgrp->dev_resources[i] != NULL)
+			kfree(drmcgrp->dev_resources[i]);
+	}
+
+	kfree(drmcgrp);
+}
+
+static inline int init_drmcgrp_single(struct drmcgrp *drmcgrp, int i)
+{
+	struct drmcgrp_device_resource *ddr = drmcgrp->dev_resources[i];
+
+	if (ddr == NULL) {
+		ddr = kzalloc(sizeof(struct drmcgrp_device_resource),
+			GFP_KERNEL);
+
+		if (!ddr)
+			return -ENOMEM;
+
+		drmcgrp->dev_resources[i] = ddr;
+	}
+
+	/* set defaults here */
+
+	return 0;
+}
+
+static inline int init_drmcgrp(struct drmcgrp *drmcgrp, struct drm_device *dev)
+{
+	int rc = 0;
+	int i;
+
+	if (dev != NULL) {
+		rc = init_drmcgrp_single(drmcgrp, dev->primary->index);
+		return rc;
+	}
+
+	for (i = 0; i <= max_minor; i++) {
+		rc = init_drmcgrp_single(drmcgrp, i);
+		if (rc)
+			return rc;
+	}
 
-	kfree(css_drmcgrp(css));
+	return 0;
 }
 
 static struct cgroup_subsys_state *
@@ -18,11 +81,18 @@ drmcgrp_css_alloc(struct cgroup_subsys_state *parent_css)
 {
 	struct drmcgrp *parent = css_drmcgrp(parent_css);
 	struct drmcgrp *drmcgrp;
+	int rc;
 
 	drmcgrp = kzalloc(sizeof(struct drmcgrp), GFP_KERNEL);
 	if (!drmcgrp)
 		return ERR_PTR(-ENOMEM);
 
+	rc = init_drmcgrp(drmcgrp, NULL);
+	if (rc) {
+		drmcgrp_css_free(&drmcgrp->css);
+		return ERR_PTR(rc);
+	}
+
 	if (!parent)
 		root_drmcgrp = drmcgrp;
 
@@ -40,3 +110,49 @@ struct cgroup_subsys drm_cgrp_subsys = {
 	.legacy_cftypes	= files,
 	.dfl_cftypes	= files,
 };
+
+int drmcgrp_register_device(struct drm_device *dev)
+{
+	struct drmcgrp_device *ddev;
+	struct cgroup_subsys_state *pos;
+	struct drmcgrp *child;
+
+	ddev = kzalloc(sizeof(struct drmcgrp_device), GFP_KERNEL);
+	if (!ddev)
+		return -ENOMEM;
+
+	ddev->dev = dev;
+	mutex_init(&ddev->mutex);
+
+	mutex_lock(&drmcgrp_mutex);
+	known_drmcgrp_devs[dev->primary->index] = ddev;
+	max_minor = max(max_minor, dev->primary->index);
+	mutex_unlock(&drmcgrp_mutex);
+
+	/* init cgroups created before registration (i.e. root cgroup) */
+	if (root_drmcgrp != NULL) {
+		init_drmcgrp(root_drmcgrp, dev);
+
+		rcu_read_lock();
+		css_for_each_child(pos, &root_drmcgrp->css) {
+			child = css_drmcgrp(pos);
+			init_drmcgrp(child, dev);
+		}
+		rcu_read_unlock();
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drmcgrp_register_device);
+
+int drmcgrp_unregister_device(struct drm_device *dev)
+{
+	mutex_lock(&drmcgrp_mutex);
+
+	kfree(known_drmcgrp_devs[dev->primary->index]);
+	known_drmcgrp_devs[dev->primary->index] = NULL;
+
+	mutex_unlock(&drmcgrp_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(drmcgrp_unregister_device);
-- 
2.21.0

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