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Subject[PATCH 3/3] tracing: Protect ftrace_trace_arrays list in trace_events.c
Date
There are multiple places where the ftrace_trace_arrays list is accessed in
trace_events.c without the trace_types_lock held.

Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Alexander Z Lam <azl@google.com>
---
kernel/trace/trace_events.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 6db3290..26351cc 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1586,6 +1586,7 @@ static void __add_event_to_tracers(struct ftrace_event_call *call,
int trace_add_event_call(struct ftrace_event_call *call)
{
int ret;
+ mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);

ret = __register_event(call, NULL);
@@ -1593,11 +1594,13 @@ int trace_add_event_call(struct ftrace_event_call *call)
__add_event_to_tracers(call, NULL);

mutex_unlock(&event_mutex);
+ mutex_unlock(&trace_types_lock);
return ret;
}

/*
- * Must be called under locking both of event_mutex and trace_event_sem.
+ * Must be called under locking of trace_types_lock, event_mutex and
+ * trace_event_sem.
*/
static void __trace_remove_event_call(struct ftrace_event_call *call)
{
@@ -1609,11 +1612,13 @@ static void __trace_remove_event_call(struct ftrace_event_call *call)
/* Remove an event_call */
void trace_remove_event_call(struct ftrace_event_call *call)
{
+ mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
down_write(&trace_event_sem);
__trace_remove_event_call(call);
up_write(&trace_event_sem);
mutex_unlock(&event_mutex);
+ mutex_unlock(&trace_types_lock);
}

#define for_each_event(event, start, end) \
@@ -1757,6 +1762,7 @@ static int trace_module_notify(struct notifier_block *self,
{
struct module *mod = data;

+ mutex_lock(&trace_types_lock);
mutex_lock(&event_mutex);
switch (val) {
case MODULE_STATE_COMING:
@@ -1767,6 +1773,7 @@ static int trace_module_notify(struct notifier_block *self,
break;
}
mutex_unlock(&event_mutex);
+ mutex_unlock(&trace_types_lock);

return 0;
}
--
1.8.3


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