tracing: Verify if trace array exists before destroying it.

A trace array can be destroyed from userspace or kernel. Verify if the
trace array exists before proceeding to destroy/remove it.

Link: http://lkml.kernel.org/r/1565805327-579-3-git-send-email-divya.indi@oracle.com
Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com>
Signed-off-by: Divya Indi <divya.indi@oracle.com>
[ Removed unneeded braces ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/module.c b/kernel/module.c
index ff2d735..6e2fd40 100644 (file)
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3728,7 +3728,6 @@ static int complete_formation(struct module *mod, struct load_info *info)
 
        module_enable_ro(mod, false);
        module_enable_nx(mod);
-       module_enable_x(mod);
 
        /* Mark state as coming so strong_try_module_get() ignores us,
         * but kallsyms etc. can see us. */
@@ -3751,6 +3750,11 @@ static int prepare_coming_module(struct module *mod)
        if (err)
                return err;
 
+       /* Make module executable after ftrace is enabled */
+       mutex_lock(&module_mutex);
+       module_enable_x(mod);
+       mutex_unlock(&module_mutex);
+
        blocking_notifier_call_chain(&module_notify_list,
                                     MODULE_STATE_COMING, mod);
        return 0;

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index db7d06a..fa4f742 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8556,17 +8556,26 @@ static int __remove_instance(struct trace_array *tr)
        return 0;
 }
 
-int trace_array_destroy(struct trace_array *tr)
+int trace_array_destroy(struct trace_array *this_tr)
 {
+       struct trace_array *tr;
        int ret;
 
-       if (!tr)
+       if (!this_tr)
                return -EINVAL;
 
        mutex_lock(&event_mutex);
        mutex_lock(&trace_types_lock);
 
-       ret = __remove_instance(tr);
+       ret = -ENODEV;
+
+       /* Making sure trace array exists before destroying it. */
+       list_for_each_entry(tr, &ftrace_trace_arrays, list) {
+               if (tr == this_tr) {
+                       ret = __remove_instance(tr);
+                       break;
+               }
+       }
 
        mutex_unlock(&trace_types_lock);
        mutex_unlock(&event_mutex);