perf: Simplify/fix perf_event_enable() event scheduling

Like perf_enable_on_exec(), perf_event_enable() event scheduling has problems
respecting the context hierarchy when trying to schedule events (for
example, it will try and add a pinned event without first removing
existing flexible events).

So simplify it by using the new ctx_resched() call which will DTRT.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 5 insertions, 26 deletions

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 12f1d4a52da9..079eb9fcaaa8 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2188,7 +2188,7 @@ static int __perf_event_enable(void *info)
         struct perf_event_context *ctx = event->ctx;
         struct perf_event *leader = event->group_leader;
         struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
-        int err;
+        struct perf_event_context *task_ctx = cpuctx->task_ctx;
 
         /*
          * There's a time window between 'ctx->is_active' check
@@ -2202,7 +2202,8 @@ static int __perf_event_enable(void *info)
         if (!ctx->is_active)
                 return -EINVAL;
 
-        raw_spin_lock(&ctx->lock);
+        perf_ctx_lock(cpuctx, task_ctx);
+        WARN_ON_ONCE(&cpuctx->ctx != ctx && task_ctx != ctx);
         update_context_time(ctx);
 
         if (event->state >= PERF_EVENT_STATE_INACTIVE)
@@ -2228,32 +2229,10 @@ static int __perf_event_enable(void *info)
         if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE)
                 goto unlock;
 
-        if (!group_can_go_on(event, cpuctx, 1)) {
-                err = -EEXIST;
-        } else {
-                if (event == leader)
-                        err = group_sched_in(event, cpuctx, ctx);
-                else
-                        err = event_sched_in(event, cpuctx, ctx);
-        }
-
-        if (err) {
-                /*
-                 * If this event can't go on and it's part of a
-                 * group, then the whole group has to come off.
-                 */
-                if (leader != event) {
-                        group_sched_out(leader, cpuctx, ctx);
-                        perf_mux_hrtimer_restart(cpuctx);
-                }
-                if (leader->attr.pinned) {
-                        update_group_times(leader);
-                        leader->state = PERF_EVENT_STATE_ERROR;
-                }
-        }
+        ctx_resched(cpuctx, task_ctx);
 
 unlock:
-        raw_spin_unlock(&ctx->lock);
+        perf_ctx_unlock(cpuctx, task_ctx);
 
         return 0;
 }