tracing: Protect ftrace_trace_arrays list in trace_events.c

commit a82274151af2b075163e3c42c828529dee311487 upstream.

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
Signed-off-by: Alexander Z Lam <azl@google.com>
Cc: Vaibhav Nagarnaik <vnagarnaik@google.com>
Cc: David Sharp <dhsharp@google.com>
Cc: Alexander Z Lam <lambchop468@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b90c993462be580898a90c38215c4164583443a9..10d3f0871b48f8d0b9f298a331994d6617a1cefe 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -240,7 +240,7 @@ 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

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 20572ed88c5c3b791bef107aab7fbc1f3b0b44d1..7944b9294599a35028c456b5cc3449e2f9bed5cb 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -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.

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index bf56c1d07df362e96a1411afd27c3008d951a197..f82d92dbd61436878ca7db6a8dac35a5061ce00d 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1011,6 +1011,7 @@ 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) {
@@ -1026,6 +1027,7 @@ 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;
@@ -1620,6 +1622,7 @@ 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);
@@ -1627,11 +1630,13 @@ 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)
 {
@@ -1643,11 +1648,13 @@ 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)                      \
@@ -1791,6 +1798,7 @@ 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:
@@ -1801,6 +1809,7 @@ static int trace_module_notify(struct notifier_block *self,
                break;
        }
        mutex_unlock(&event_mutex);
+       mutex_unlock(&trace_types_lock);
 
        return 0;
 }