[PATCH 06/11] perf: Move cgroup init before PMU ->event_init()

[Matt Fleming]

From: Matt Fleming <matt.fleming@xxxxxxxxx>

The Intel QoS PMU needs to know whether an event is part of a cgroup
during ->event_init(), because tasks in the same cgroup share a
monitoring ID.

Move the cgroup initialisation before calling into the PMU driver.

Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
---
 kernel/events/core.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 7925f21cee7f..8a07f51a23ff 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6859,7 +6859,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 		 struct perf_event *group_leader,
 		 struct perf_event *parent_event,
 		 perf_overflow_handler_t overflow_handler,
-		 void *context)
+		 void *context, bool cgroup, pid_t pid)
 {
 	struct pmu *pmu;
 	struct perf_event *event;
@@ -6952,6 +6952,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
 	if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
 		goto err_ns;
 
+	if (cgroup) {
+		err = perf_cgroup_connect(pid, event, attr, group_leader);
+		if (err)
+			goto err_ns;
+	}
+
 	pmu = perf_init_event(event);
 	if (!pmu)
 		goto err_ns;
@@ -6975,6 +6981,8 @@ err_pmu:
 		event->destroy(event);
 	module_put(pmu->module);
 err_ns:
+	if (is_cgroup_event(event))
+		perf_detach_cgroup(event);
 	if (event->ns)
 		put_pid_ns(event->ns);
 	kfree(event);
@@ -7178,6 +7186,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	struct fd group = {NULL, 0};
 	struct task_struct *task = NULL;
 	struct pmu *pmu;
+	bool cgroup = false;
 	int event_fd;
 	int move_group = 0;
 	int err;
@@ -7247,21 +7256,16 @@ SYSCALL_DEFINE5(perf_event_open,
 
 	get_online_cpus();
 
+	if (flags & PERF_FLAG_PID_CGROUP)
+		cgroup = true;
+
 	event = perf_event_alloc(&attr, cpu, task, group_leader, NULL,
-				 NULL, NULL);
+				 NULL, NULL, cgroup, pid);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
 		goto err_cpus;
 	}
 
-	if (flags & PERF_FLAG_PID_CGROUP) {
-		err = perf_cgroup_connect(pid, event, &attr, group_leader);
-		if (err) {
-			__free_event(event);
-			goto err_cpus;
-		}
-	}
-
 	if (is_sampling_event(event)) {
 		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
 			err = -ENOTSUPP;
@@ -7461,7 +7465,7 @@ perf_event_create_kernel_counter(struct perf_event_attr *attr, int cpu,
 	 */
 
 	event = perf_event_alloc(attr, cpu, task, NULL, NULL,
-				 overflow_handler, context);
+				 overflow_handler, context, false, -1);
 	if (IS_ERR(event)) {
 		err = PTR_ERR(event);
 		goto err;
@@ -7792,7 +7796,7 @@ inherit_event(struct perf_event *parent_event,
 					   parent_event->cpu,
 					   child,
 					   group_leader, parent_event,
-				           NULL, NULL);
+				           NULL, NULL, false, -1);
 	if (IS_ERR(child_event))
 		return child_event;
 
-- 
1.9.3

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