perf: Make perf_cgroup_from_task() global

Move perf_cgroup_from_task() from kernel/events/ to include/linux/ along
with the necessary struct definitions, so that it can be used by the PMU
code.

When the upcoming Intel Cache Monitoring PMU driver assigns monitoring
IDs to perf events, it needs to be able to check whether any two
monitoring events overlap (say, a cgroup and task event), which means we
need to be able to lookup the cgroup associated with a task (if any).

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kanaka Juvva <kanaka.d.juvva@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Link: http://lkml.kernel.org/r/1422038748-21397-2-git-send-email-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/perf_event.h

@@ -53,6 +53,7 @@ struct perf_guest_info_callbacks {
 #include <linux/sysfs.h>
 #include <linux/perf_regs.h>
 #include <linux/workqueue.h>
+#include <linux/cgroup.h>
 #include <asm/local.h>
 
 struct perf_callchain_entry {
@@ -547,6 +548,35 @@ struct perf_output_handle {
 	int				page;
 };
 
+#ifdef CONFIG_CGROUP_PERF
+
+/*
+ * perf_cgroup_info keeps track of time_enabled for a cgroup.
+ * This is a per-cpu dynamically allocated data structure.
+ */
+struct perf_cgroup_info {
+	u64				time;
+	u64				timestamp;
+};
+
+struct perf_cgroup {
+	struct cgroup_subsys_state	css;
+	struct perf_cgroup_info	__percpu *info;
+};
+
+/*
+ * Must ensure cgroup is pinned (css_get) before calling
+ * this function. In other words, we cannot call this function
+ * if there is no cgroup event for the current CPU context.
+ */
+static inline struct perf_cgroup *
+perf_cgroup_from_task(struct task_struct *task)
+{
+	return container_of(task_css(task, perf_event_cgrp_id),
+			    struct perf_cgroup, css);
+}
+#endif /* CONFIG_CGROUP_PERF */
+
 #ifdef CONFIG_PERF_EVENTS
 
 extern int perf_pmu_register(struct pmu *pmu, const char *name, int type);

kernel/events/core.c

@@ -34,11 +34,11 @@
 #include <linux/syscalls.h>
 #include <linux/anon_inodes.h>
 #include <linux/kernel_stat.h>
+#include <linux/cgroup.h>
 #include <linux/perf_event.h>
 #include <linux/ftrace_event.h>
 #include <linux/hw_breakpoint.h>
 #include <linux/mm_types.h>
-#include <linux/cgroup.h>
 #include <linux/module.h>
 #include <linux/mman.h>
 #include <linux/compat.h>
@@ -351,32 +351,6 @@ static void perf_ctx_unlock(struct perf_cpu_context *cpuctx,
 
 #ifdef CONFIG_CGROUP_PERF
 
-/*
- * perf_cgroup_info keeps track of time_enabled for a cgroup.
- * This is a per-cpu dynamically allocated data structure.
- */
-struct perf_cgroup_info {
-	u64				time;
-	u64				timestamp;
-};
-
-struct perf_cgroup {
-	struct cgroup_subsys_state	css;
-	struct perf_cgroup_info	__percpu *info;
-};
-
-/*
- * Must ensure cgroup is pinned (css_get) before calling
- * this function. In other words, we cannot call this function
- * if there is no cgroup event for the current CPU context.
- */
-static inline struct perf_cgroup *
-perf_cgroup_from_task(struct task_struct *task)
-{
-	return container_of(task_css(task, perf_event_cgrp_id),
-			    struct perf_cgroup, css);
-}
-
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {