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-rw-r--r--kernel/events/core.c56
1 files changed, 47 insertions, 9 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 417a96bf3d41..142dbabc1615 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7645,16 +7645,9 @@ SYSCALL_DEFINE5(perf_event_open,
perf_remove_from_context(group_leader, false);
- /*
- * Removing from the context ends up with disabled
- * event. What we want here is event in the initial
- * startup state, ready to be add into new context.
- */
- perf_event__state_init(group_leader);
list_for_each_entry(sibling, &group_leader->sibling_list,
group_entry) {
perf_remove_from_context(sibling, false);
- perf_event__state_init(sibling);
put_ctx(gctx);
}
} else {
@@ -7670,13 +7663,31 @@ SYSCALL_DEFINE5(perf_event_open,
*/
synchronize_rcu();
- perf_install_in_context(ctx, group_leader, group_leader->cpu);
- get_ctx(ctx);
+ /*
+ * Install the group siblings before the group leader.
+ *
+ * Because a group leader will try and install the entire group
+ * (through the sibling list, which is still in-tact), we can
+ * end up with siblings installed in the wrong context.
+ *
+ * By installing siblings first we NO-OP because they're not
+ * reachable through the group lists.
+ */
list_for_each_entry(sibling, &group_leader->sibling_list,
group_entry) {
+ perf_event__state_init(sibling);
perf_install_in_context(ctx, sibling, sibling->cpu);
get_ctx(ctx);
}
+
+ /*
+ * Removing from the context ends up with disabled
+ * event. What we want here is event in the initial
+ * startup state, ready to be add into new context.
+ */
+ perf_event__state_init(group_leader);
+ perf_install_in_context(ctx, group_leader, group_leader->cpu);
+ get_ctx(ctx);
}
perf_install_in_context(ctx, event, event->cpu);
@@ -7806,8 +7817,35 @@ void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
list_add(&event->migrate_entry, &events);
}
+ /*
+ * Wait for the events to quiesce before re-instating them.
+ */
synchronize_rcu();
+ /*
+ * Re-instate events in 2 passes.
+ *
+ * Skip over group leaders and only install siblings on this first
+ * pass, siblings will not get enabled without a leader, however a
+ * leader will enable its siblings, even if those are still on the old
+ * context.
+ */
+ list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
+ if (event->group_leader == event)
+ continue;
+
+ list_del(&event->migrate_entry);
+ if (event->state >= PERF_EVENT_STATE_OFF)
+ event->state = PERF_EVENT_STATE_INACTIVE;
+ account_event_cpu(event, dst_cpu);
+ perf_install_in_context(dst_ctx, event, dst_cpu);
+ get_ctx(dst_ctx);
+ }
+
+ /*
+ * Once all the siblings are setup properly, install the group leaders
+ * to make it go.
+ */
list_for_each_entry_safe(event, tmp, &events, migrate_entry) {
list_del(&event->migrate_entry);
if (event->state >= PERF_EVENT_STATE_OFF)