Commit-ID: b53e5129c4c7ab47ec4f709fd8f5784ca45fb46d
Gitweb: http://git.kernel.org/tip/b53e5129c4c7ab47ec4f709fd8f5784ca45fb46d
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Sun, 23 Apr 2017 12:17:13 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Sun, 23 Apr 2017 19:11:28 +0200
trace/perf: Cure hotplug lock ordering issues
The get_online_cpus() rework unearthed lock ordering issues.
Reorder hotpluglock and event_mutex() to avoid circular locking
dependencies and convert static_key_slow_dec() to the cpuslocked version to
avoid hotplug lock recursion.
That also requires to protect the call to perf_trace_destroy() against cpu
hotplug.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
kernel/events/core.c | 2 ++
kernel/trace/trace_events.c | 6 ++++++
kernel/tracepoint.c | 4 ++--
3 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c
index b5b4f52f..997123c 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7783,7 +7783,9 @@ EXPORT_SYMBOL_GPL(perf_tp_event);
static void tp_perf_event_destroy(struct perf_event *event)
{
+ get_online_cpus();
perf_trace_destroy(event);
+ put_online_cpus();
}
static int perf_tp_event_init(struct perf_event *event)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 9311654..8156bfd 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -747,9 +747,11 @@ static int __ftrace_set_clr_event(struct trace_array *tr, const char *match,
{
int ret;
+ get_online_cpus();
mutex_lock(&event_mutex);
ret = __ftrace_set_clr_event_nolock(tr, match, sub, event, set);
mutex_unlock(&event_mutex);
+ put_online_cpus();
return ret;
}
@@ -1039,11 +1041,13 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
case 0:
case 1:
ret = -ENODEV;
+ get_online_cpus();
mutex_lock(&event_mutex);
file = event_file_data(filp);
if (likely(file))
ret = ftrace_event_enable_disable(file, val);
mutex_unlock(&event_mutex);
+ put_online_cpus();
break;
default:
@@ -2902,6 +2906,7 @@ early_event_add_tracer(struct dentry *parent, struct trace_array *tr)
int event_trace_del_tracer(struct trace_array *tr)
{
+ get_online_cpus();
mutex_lock(&event_mutex);
/* Disable any event triggers and associated soft-disabled events */
@@ -2924,6 +2929,7 @@ int event_trace_del_tracer(struct trace_array *tr)
tr->event_dir = NULL;
mutex_unlock(&event_mutex);
+ put_online_cpus();
return 0;
}
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 685c50a..10ce910 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -220,7 +220,7 @@ static int tracepoint_add_func(struct tracepoint *tp,
*/
rcu_assign_pointer(tp->funcs, tp_funcs);
if (!static_key_enabled(&tp->key))
- static_key_slow_inc(&tp->key);
+ static_key_slow_inc_cpuslocked(&tp->key);
release_probes(old);
return 0;
}
@@ -250,7 +250,7 @@ static int tracepoint_remove_func(struct tracepoint *tp,
tp->unregfunc();
if (static_key_enabled(&tp->key))
- static_key_slow_dec(&tp->key);
+ static_key_slow_dec_cpuslocked(&tp->key);
}
rcu_assign_pointer(tp->funcs, tp_funcs);
release_probes(old);
--
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