[PATCH 10/11] drm, cgroup: add update trigger after limit change

Kenny Ho Kenny.Ho at amd.com
Fri Feb 14 15:56:49 UTC 2020


Before this commit, drmcg limits are updated but enforcement is delayed
until the next time the driver check against the new limit.  While this
is sufficient for certain resources, a more proactive enforcement may be
needed for other resources.

Introducing an optional drmcg_limit_updated callback for the DRM
drivers.  When defined, it will be called in two scenarios:
1) When limits are updated for a particular cgroup, the callback will be
triggered for each task in the updated cgroup.
2) When a task is migrated from one cgroup to another, the callback will
be triggered for each resource type for the migrated task.

Change-Id: I0ce7c4e5a04c31bd0f8d9853a383575d4bc9a3fa
Signed-off-by: Kenny Ho <Kenny.Ho at amd.com>
---
 include/drm/drm_drv.h | 10 ++++++++
 kernel/cgroup/drm.c   | 59 ++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 1f65ac4d9bbf..e7333143e722 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -724,6 +724,16 @@ struct drm_driver {
 	void (*drmcg_custom_init)(struct drm_device *dev,
 			struct drmcg_props *props);
 
+	/**
+	 * @drmcg_limit_updated
+	 *
+	 * Optional callback
+	 */
+	void (*drmcg_limit_updated)(struct drm_device *dev,
+			struct task_struct *task,
+			struct drmcg_device_resource *ddr,
+			enum drmcg_res_type res_type);
+
 	/**
 	 * @gem_vm_ops: Driver private ops for this object
 	 *
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index a4e88a3704bb..d3fa23b71f5f 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -133,6 +133,26 @@ static inline void drmcg_update_cg_tree(struct drm_device *dev)
 	mutex_unlock(&cgroup_mutex);
 }
 
+static void drmcg_limit_updated(struct drm_device *dev, struct drmcg *drmcg,
+		enum drmcg_res_type res_type)
+{
+	struct drmcg_device_resource *ddr =
+		drmcg->dev_resources[dev->primary->index];
+	struct css_task_iter it;
+	struct task_struct *task;
+
+	if (dev->driver->drmcg_limit_updated == NULL)
+		return;
+
+	css_task_iter_start(&drmcg->css.cgroup->self,
+			CSS_TASK_ITER_PROCS, &it);
+	while ((task = css_task_iter_next(&it))) {
+		dev->driver->drmcg_limit_updated(dev, task,
+				ddr, res_type);
+	}
+	css_task_iter_end(&it);
+}
+
 static void drmcg_calculate_effective_lgpu(struct drm_device *dev,
 		const unsigned long *free_static,
 		const unsigned long *free_weighted,
@@ -230,6 +250,8 @@ static void drmcg_apply_effective_lgpu(struct drm_device *dev)
 			bitmap_copy(ddr->lgpu_eff, ddr->lgpu_stg, capacity);
 			ddr->lgpu_count_eff =
 				bitmap_weight(ddr->lgpu_eff, capacity);
+
+			drmcg_limit_updated(dev, drmcg, DRMCG_TYPE_LGPU);
 		}
 	}
 	rcu_read_unlock();
@@ -686,7 +708,6 @@ static void drmcg_nested_limit_parse(struct kernfs_open_file *of,
 	}
 }
 
-
 /**
  * drmcg_limit_write - parse cgroup interface files to obtain user config
  *
@@ -879,10 +900,46 @@ static int drmcg_css_online(struct cgroup_subsys_state *css)
 	return drm_minor_for_each(&drmcg_online_fn, css_to_drmcg(css));
 }
 
+static int drmcg_attach_fn(int id, void *ptr, void *data)
+{
+	struct drm_minor *minor = ptr;
+	struct task_struct *task = data;
+	struct drm_device *dev;
+
+	if (minor->type != DRM_MINOR_PRIMARY)
+		return 0;
+
+	dev = minor->dev;
+
+	if (dev->driver->drmcg_limit_updated) {
+		struct drmcg *drmcg = drmcg_get(task);
+		struct drmcg_device_resource *ddr =
+			drmcg->dev_resources[minor->index];
+		enum drmcg_res_type type;
+
+		for (type = 0; type < __DRMCG_TYPE_LAST; type++)
+			dev->driver->drmcg_limit_updated(dev, task, ddr, type);
+
+		drmcg_put(drmcg);
+	}
+
+	return 0;
+}
+
+static void drmcg_attach(struct cgroup_taskset *tset)
+{
+	struct task_struct *task;
+	struct cgroup_subsys_state *css;
+
+	cgroup_taskset_for_each(task, css, tset)
+		drm_minor_for_each(&drmcg_attach_fn, task);
+}
+
 struct cgroup_subsys drm_cgrp_subsys = {
 	.css_alloc	= drmcg_css_alloc,
 	.css_free	= drmcg_css_free,
 	.css_online	= drmcg_css_online,
+	.attach		= drmcg_attach,
 	.early_init	= false,
 	.legacy_cftypes	= files,
 	.dfl_cftypes	= files,
-- 
2.25.0



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