From 652884fe0c7bd57f534c5fe68d6def0dc8c4b7ed Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 23 Jan 2015 11:20:10 +0100
Subject: [PATCH] perf: Add a bit of paranoia
Add a few WARN()s to catch things that should never happen.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20150123125834.150481799@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/events/core.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b4a696c4dc76e..b358cb38e4a55 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1275,6 +1275,8 @@ static void perf_group_attach(struct perf_event *event)
if (group_leader == event)
return;
+ WARN_ON_ONCE(group_leader->ctx != event->ctx);
+
if (group_leader->group_flags & PERF_GROUP_SOFTWARE &&
!is_software_event(event))
group_leader->group_flags &= ~PERF_GROUP_SOFTWARE;
@@ -1296,6 +1298,10 @@ static void
list_del_event(struct perf_event *event, struct perf_event_context *ctx)
{
struct perf_cpu_context *cpuctx;
+
+ WARN_ON_ONCE(event->ctx != ctx);
+ lockdep_assert_held(&ctx->lock);
+
/*
* We can have double detach due to exit/hot-unplug + close.
*/
@@ -1380,6 +1386,8 @@ static void perf_group_detach(struct perf_event *event)
/* Inherit group flags from the previous leader */
sibling->group_flags = event->group_flags;
+
+ WARN_ON_ONCE(sibling->ctx != event->ctx);
}
out:
@@ -1442,6 +1450,10 @@ event_sched_out(struct perf_event *event,
{
u64 tstamp = perf_event_time(event);
u64 delta;
+
+ WARN_ON_ONCE(event->ctx != ctx);
+ lockdep_assert_held(&ctx->lock);
+
/*
* An event which could not be activated because of
* filter mismatch still needs to have its timings
@@ -7822,14 +7834,19 @@ static void perf_free_event(struct perf_event *event,
put_event(parent);
+ raw_spin_lock_irq(&ctx->lock);
perf_group_detach(event);
list_del_event(event, ctx);
+ raw_spin_unlock_irq(&ctx->lock);
free_event(event);
}
/*
- * free an unexposed, unused context as created by inheritance by
+ * Free an unexposed, unused context as created by inheritance by
* perf_event_init_task below, used by fork() in case of fail.
+ *
+ * Not all locks are strictly required, but take them anyway to be nice and
+ * help out with the lockdep assertions.
*/
void perf_event_free_task(struct task_struct *task)
{
--
2.30.2