[PATCH v2 15/32] perf/core: add hooks to expose architecture specific features in perf_cgroup

[David Carrillo-Cisneros <davidcc@google.com>]

The hooks allows architectures to extend the behavior of the
perf subsystem.

In this patch series, the hooks will be used by Intel's CQM PMU to
provide support for the llc_occupancy event.

Reviewed-by: Stephane Eranian <eranian@google.com>
Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
---
 include/linux/perf_event.h | 28 +++++++++++++++++++++++++++-
 kernel/events/core.c       | 27 +++++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 02b8e24..60dbd5d 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -762,7 +762,9 @@ struct perf_cgroup_info {
 };
 
 struct perf_cgroup {
-	struct cgroup_subsys_state	css;
+	/* Architecture specific information. */
+	void				 *arch_info;
+	struct cgroup_subsys_state	 css;
 	struct perf_cgroup_info	__percpu *info;
 };
 
@@ -1332,4 +1334,28 @@ _name##_show(struct device *dev,					\
 									\
 static struct device_attribute format_attr_##_name = __ATTR_RO(_name)
 
+
+/*
+ * Hooks for architecture specific extensions for perf_cgroup.
+ */
+#ifndef perf_cgroup_arch_css_alloc
+# define perf_cgroup_arch_css_alloc(parent_css, new_css) 0
+#endif
+
+#ifndef perf_cgroup_arch_css_online
+# define perf_cgroup_arch_css_online(css) 0
+#endif
+
+#ifndef perf_cgroup_arch_css_offline
+# define perf_cgroup_arch_css_offline(css) do { } while (0)
+#endif
+
+#ifndef perf_cgroup_arch_css_released
+# define perf_cgroup_arch_css_released(css) do { } while (0)
+#endif
+
+#ifndef perf_cgroup_arch_css_free
+# define perf_cgroup_arch_css_free(css) do { } while (0)
+#endif
+
 #endif /* _LINUX_PERF_EVENT_H */
diff --git a/kernel/events/core.c b/kernel/events/core.c
index d464e57..b249251 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10378,6 +10378,7 @@ static struct cgroup_subsys_state *
 perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 {
 	struct perf_cgroup *jc;
+	int ret;
 
 	jc = kzalloc(sizeof(*jc), GFP_KERNEL);
 	if (!jc)
@@ -10389,13 +10390,36 @@ perf_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 		return ERR_PTR(-ENOMEM);
 	}
 
+	jc->arch_info = NULL;
+
+	ret = perf_cgroup_arch_css_alloc(parent_css, &jc->css);
+	if (ret)
+		return ERR_PTR(ret);
+
 	return &jc->css;
 }
 
+static int perf_cgroup_css_online(struct cgroup_subsys_state *css)
+{
+	return perf_cgroup_arch_css_online(css);
+}
+
+static void perf_cgroup_css_offline(struct cgroup_subsys_state *css)
+{
+	perf_cgroup_arch_css_offline(css);
+}
+
+static void perf_cgroup_css_released(struct cgroup_subsys_state *css)
+{
+	perf_cgroup_arch_css_released(css);
+}
+
 static void perf_cgroup_css_free(struct cgroup_subsys_state *css)
 {
 	struct perf_cgroup *jc = container_of(css, struct perf_cgroup, css);
 
+	perf_cgroup_arch_css_free(css);
+
 	free_percpu(jc->info);
 	kfree(jc);
 }
@@ -10420,6 +10444,9 @@ static void perf_cgroup_attach(struct cgroup_taskset *tset)
 
 struct cgroup_subsys perf_event_cgrp_subsys = {
 	.css_alloc	= perf_cgroup_css_alloc,
+	.css_online	= perf_cgroup_css_online,
+	.css_offline	= perf_cgroup_css_offline,
+	.css_released	= perf_cgroup_css_released,
 	.css_free	= perf_cgroup_css_free,
 	.attach		= perf_cgroup_attach,
 };
-- 
2.8.0.rc3.226.g39d4020