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Commit a8227415 authored by Alexander Z Lam's avatar Alexander Z Lam Committed by Steven Rostedt
Browse files

tracing: Protect ftrace_trace_arrays list in trace_events.c 

There are multiple places where the ftrace_trace_arrays list is accessed in
trace_events.c without the trace_types_lock held.

Link: http://lkml.kernel.org/r/1372732674-22726-1-git-send-email-azl@google.com



Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Cc: stable@vger.kernel.org # 3.10
Signed-off-by: default avatarAlexander Z Lam <azl@google.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 2d71619c

kernel/trace/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -266,7 +266,7 @@ static struct tracer *trace_types __read_mostly; 
/*

 * trace_types_lock is used to protect the trace_types list.

 */

static DEFINE_MUTEX(trace_types_lock);

DEFINE_MUTEX(trace_types_lock);



/*

 * serialize the access of the ring buffer

kernel/trace/trace.h

+2 −0
Original line number Diff line number Diff line
@@ -224,6 +224,8 @@ enum { 


extern struct list_head ftrace_trace_arrays;



extern struct mutex trace_types_lock;



/*

 * The global tracer (top) should be the first trace array added,

 * but we check the flag anyway.

kernel/trace/trace_events.c

+10 −1
Original line number Diff line number Diff line
@@ -1008,6 +1008,7 @@ static int subsystem_open(struct inode *inode, struct file *filp) 
	int ret;



	/* Make sure the system still exists */

	mutex_lock(&trace_types_lock);

	mutex_lock(&event_mutex);

	list_for_each_entry(tr, &ftrace_trace_arrays, list) {

		list_for_each_entry(dir, &tr->systems, list) {
@@ -1023,6 +1024,7 @@ static int subsystem_open(struct inode *inode, struct file *filp) 
	}

 exit_loop:

	mutex_unlock(&event_mutex);

	mutex_unlock(&trace_types_lock);



	if (!system)

		return -ENODEV;
@@ -1617,6 +1619,7 @@ 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);
@@ -1624,11 +1627,13 @@ 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)

{
@@ -1640,11 +1645,13 @@ 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)			\
@@ -1788,6 +1795,7 @@ 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:
@@ -1798,6 +1806,7 @@ static int trace_module_notify(struct notifier_block *self, 
		break;

	}

	mutex_unlock(&event_mutex);

	mutex_unlock(&trace_types_lock);



	return 0;

}