[for-next][PATCH 10/10] tracing: Fix rcu handling of event_trigger_data filter field

Steven Rostedt
2013-12-23T21:39:22Z

[-- Attachment #1: 0010-tracing-Fix-rcu-handling-of-event_trigger_data-filte.patch --]
[-- Type: text/plain, Size: 2288 bytes --]

From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>

The filter field of the event_trigger_data structure is protected under
RCU sched locks. It was not annotated as such, and after doing so,
sparse pointed out several locations that required fix ups.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.h | 2 +-
kernel/trace/trace_events_trigger.c | 8 +++++---
2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 0380cab..02b592f 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1057,7 +1057,7 @@ struct event_trigger_data {
int ref;
struct event_trigger_ops *ops;
struct event_command *cmd_ops;
- struct event_filter *filter;
+ struct event_filter __rcu *filter;
char *filter_str;
void *private_data;
struct list_head list;
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 12ac8a5..f6dd115 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -67,6 +67,7 @@ event_triggers_call(struct ftrace_event_file *file, void *rec)
{
struct event_trigger_data *data;
enum event_trigger_type tt = ETT_NONE;
+ struct event_filter *filter;

if (list_empty(&file->triggers))
return tt;
@@ -76,7 +77,8 @@ event_triggers_call(struct ftrace_event_file *file, void *rec)
data->ops->func(data);
continue;
}
- if (data->filter && !filter_match_preds(data->filter, rec))
+ filter = rcu_dereference(data->filter);
+ if (filter && !filter_match_preds(filter, rec))
continue;
if (data->cmd_ops->post_trigger) {
tt |= data->cmd_ops->trigger_type;
@@ -703,7 +705,7 @@ static int set_trigger_filter(char *filter_str,
if (ret)
goto out;
assign:
- tmp = data->filter;
+ tmp = rcu_access_pointer(data->filter);

rcu_assign_pointer(data->filter, filter);

@@ -719,7 +721,7 @@ static int set_trigger_filter(char *filter_str,
if (filter_str) {
data->filter_str = kstrdup(filter_str, GFP_KERNEL);
if (!data->filter_str) {
- free_event_filter(data->filter);
+ free_event_filter(rcu_access_pointer(data->filter));
data->filter = NULL;
ret = -ENOMEM;
}
--
1.8.4.3