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

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

Since many parts of the DRM subsystem has vendor-specific
implementations, we introduce mechanisms for vendor to register their
specific resources and control files to the DRM cgroup subsystem.  A
vendor will register itself with the DRM cgroup subsystem first before
registering individual DRM devices to the cgroup subsystem.

In addition to the cgroup_subsys_state that is common to all DRM
devices, a device-specific state is introduced and it is allocated
according to the vendor of the device.

Change-Id: I908ee6975ea0585e4c30eafde4599f87094d8c65
Signed-off-by: Kenny Ho <Kenny.Ho@amd.com>
---
 include/drm/drm_cgroup.h      | 39 ++++++++++++++++
 include/drm/drmcgrp_vendors.h |  7 +++
 include/linux/cgroup_drm.h    | 26 +++++++++++
 kernel/cgroup/drm.c           | 84 +++++++++++++++++++++++++++++++++++
 4 files changed, 156 insertions(+)
 create mode 100644 include/drm/drm_cgroup.h
 create mode 100644 include/drm/drmcgrp_vendors.h

diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
new file mode 100644
index 000000000000..26cbea7059a6
--- /dev/null
+++ b/include/drm/drm_cgroup.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: MIT
+ * Copyright 2018 Advanced Micro Devices, Inc.
+ */
+#ifndef __DRM_CGROUP_H__
+#define __DRM_CGROUP_H__
+
+#define DRMCGRP_VENDOR(_x) _x ## _drmcgrp_vendor_id,
+enum drmcgrp_vendor_id {
+#include <drm/drmcgrp_vendors.h>
+	DRMCGRP_VENDOR_COUNT,
+};
+#undef DRMCGRP_VENDOR
+
+#define DRMCGRP_VENDOR(_x) extern struct drmcgrp_vendor _x ## _drmcgrp_vendor;
+#include <drm/drmcgrp_vendors.h>
+#undef DRMCGRP_VENDOR
+
+
+
+#ifdef CONFIG_CGROUP_DRM
+
+extern struct drmcgrp_vendor *drmcgrp_vendors[];
+
+int drmcgrp_register_vendor(struct drmcgrp_vendor *vendor, enum drmcgrp_vendor_id id);
+int drmcgrp_register_device(struct drm_device *device, enum drmcgrp_vendor_id id);
+
+#else
+static int drmcgrp_register_vendor(struct drmcgrp_vendor *vendor, enum drmcgrp_vendor_id id)
+{
+	return 0;
+}
+
+static int drmcgrp_register_device(struct drm_device *device, enum drmcgrp_vendor_id id)
+{
+	return 0;
+}
+
+#endif /* CONFIG_CGROUP_DRM */
+#endif /* __DRM_CGROUP_H__ */
diff --git a/include/drm/drmcgrp_vendors.h b/include/drm/drmcgrp_vendors.h
new file mode 100644
index 000000000000..b04d8649851b
--- /dev/null
+++ b/include/drm/drmcgrp_vendors.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: MIT
+ * Copyright 2018 Advanced Micro Devices, Inc.
+ */
+#if IS_ENABLED(CONFIG_CGROUP_DRM)
+
+
+#endif
diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
index 79ab38b0f46d..a776662d9593 100644
--- a/include/linux/cgroup_drm.h
+++ b/include/linux/cgroup_drm.h
@@ -6,10 +6,36 @@
 
 #ifdef CONFIG_CGROUP_DRM
 
+#include <linux/mutex.h>
 #include <linux/cgroup.h>
+#include <drm/drm_file.h>
+#include <drm/drm_cgroup.h>
+
+/* limit defined per the way drm_minor_alloc operates */
+#define MAX_DRM_DEV (64 * DRM_MINOR_RENDER)
+
+struct drmcgrp_device {
+	enum drmcgrp_vendor_id	vid;
+	struct drm_device	*dev;
+	struct mutex		mutex;
+};
+
+/* vendor-common resource counting goes here */
+/* this struct should be included in the vendor specific resource */
+struct drmcgrp_device_resource {
+	struct drmcgrp_device	*ddev;
+};
+
+struct drmcgrp_vendor {
+	struct cftype *(*get_cftypes)(void);
+	struct drmcgrp_device_resource *(*alloc_dev_resource)(void);
+	void (*free_dev_resource)(struct drmcgrp_device_resource *dev_resource);
+};
+
 
 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 d9e194b9aead..f9630cc389bc 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -1,8 +1,30 @@
 // SPDX-License-Identifier: MIT
 // Copyright 2018 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>
+
+/* generate an array of drm cgroup vendor pointers */
+#define DRMCGRP_VENDOR(_x)[_x ## _drmcgrp_vendor_id] = NULL,
+struct drmcgrp_vendor *drmcgrp_vendors[] = {
+#include <drm/drmcgrp_vendors.h>
+};
+#undef DRMCGRP_VENDOR
+EXPORT_SYMBOL(drmcgrp_vendors);
+
+static DEFINE_MUTEX(drmcgrp_mutex);
+
+/* indexed by drm_minor for access speed */
+static struct drmcgrp_device	*known_drmcgrp_devs[MAX_DRM_DEV];
+
+static int max_minor;
+
 
 static u64 drmcgrp_test_read(struct cgroup_subsys_state *css,
 					struct cftype *cft)
@@ -13,6 +35,12 @@ static u64 drmcgrp_test_read(struct cgroup_subsys_state *css,
 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)
+			drmcgrp_vendors[known_drmcgrp_devs[i]->vid]->free_dev_resource(drmcgrp->dev_resources[i]);
+	}
 
 	kfree(css_drmcgrp(css));
 }
@@ -21,11 +49,27 @@ static struct cgroup_subsys_state *
 drmcgrp_css_alloc(struct cgroup_subsys_state *parent_css)
 {
 	struct drmcgrp *drmcgrp;
+	int i;
 
 	drmcgrp = kzalloc(sizeof(struct drmcgrp), GFP_KERNEL);
 	if (!drmcgrp)
 		return ERR_PTR(-ENOMEM);
 
+	for (i = 0; i <= max_minor; i++) {
+		if (known_drmcgrp_devs[i] != NULL) {
+			struct drmcgrp_device_resource *ddr =
+				drmcgrp_vendors[known_drmcgrp_devs[i]->vid]->alloc_dev_resource();
+
+			if (IS_ERR(ddr)) {
+				drmcgrp_css_free(&drmcgrp->css);
+				return ERR_PTR(-ENOMEM);
+			}
+
+			drmcgrp->dev_resources[i] = ddr;
+			drmcgrp->dev_resources[i]->ddev = known_drmcgrp_devs[i];
+		}
+	}
+
 	return &drmcgrp->css;
 }
 
@@ -44,3 +88,43 @@ struct cgroup_subsys drm_cgrp_subsys = {
 	.legacy_cftypes	= files,
 	.dfl_cftypes	= files,
 };
+
+int drmcgrp_register_vendor(struct drmcgrp_vendor *vendor, enum drmcgrp_vendor_id id)
+{
+	int rc = 0;
+	struct cftype *cfts;
+
+	// TODO: root css created before any registration
+	if (drmcgrp_vendors[id] == NULL) {
+		drmcgrp_vendors[id] = vendor;
+		cfts = vendor->get_cftypes();
+		if (cfts != NULL)
+			rc = cgroup_add_legacy_cftypes(&drm_cgrp_subsys, cfts);
+	}
+	return rc;
+}
+EXPORT_SYMBOL(drmcgrp_register_vendor);
+
+
+int drmcgrp_register_device(struct drm_device *dev, enum drmcgrp_vendor_id id)
+{
+	struct drmcgrp_device *ddev;
+
+	ddev = kzalloc(sizeof(struct drmcgrp_device), GFP_KERNEL);
+	if (!ddev)
+		return -ENOMEM;
+
+	mutex_lock(&drmcgrp_mutex);
+
+	ddev->vid = id;
+	ddev->dev = dev;
+	mutex_init(&ddev->mutex);
+
+	known_drmcgrp_devs[dev->primary->index] = ddev;
+
+	max_minor = max(max_minor, dev->primary->index);
+
+	mutex_unlock(&drmcgrp_mutex);
+	return 0;
+}
+EXPORT_SYMBOL(drmcgrp_register_device);
-- 
2.19.1

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