tracing/events: clean up for ftrace_set_clr_event()

Add a helper function __ftrace_set_clr_event(), and replace some
ftrace_set_clr_event() calls with this helper, thus we don't need any
kstrdup() or kmalloc().

As a side effect, this patch fixes an issue in self tests code, which is
similar to the one fixed in commit d6bf81ef0f7474434c2a049e8bf3c9146a14dd96
("tracing: append ":*" to internal setting of system events")

It's a small issue and won't cause any bug in fact, but we should do things
right anyway.

[ Impact: prevent spurious event-enabling in tracing self-tests ]

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A03998E.3020503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 46 insertions, 80 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 8d0fae3af595..45f1099386b6 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -111,11 +111,44 @@ static void ftrace_event_enable_disable(struct ftrace_event_call *call,
         }
 }
 
-static int ftrace_set_clr_event(char *buf, int set)
+/*
+ * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
+ */
+static int __ftrace_set_clr_event(const char *match, const char *sub,
+                                  const char *event, int set)
 {
         struct ftrace_event_call *call;
+        int ret;
+
+        mutex_lock(&event_mutex);
+        list_for_each_entry(call, &ftrace_events, list) {
+
+                if (!call->name || !call->regfunc)
+                        continue;
+
+                if (match &&
+                    strcmp(match, call->name) != 0 &&
+                    strcmp(match, call->system) != 0)
+                        continue;
+
+                if (sub && strcmp(sub, call->system) != 0)
+                        continue;
+
+                if (event && strcmp(event, call->name) != 0)
+                        continue;
+
+                ftrace_event_enable_disable(call, set);
+
+                ret = 0;
+        }
+        mutex_unlock(&event_mutex);
+
+        return ret;
+}
+
+static int ftrace_set_clr_event(char *buf, int set)
+{
         char *event = NULL, *sub = NULL, *match;
-        int ret = -EINVAL;
 
         /*
          * The buf format can be <subsystem>:<event-name>
@@ -141,30 +174,7 @@ static int ftrace_set_clr_event(char *buf, int set)
                         event = NULL;
         }
 
-        mutex_lock(&event_mutex);
-        list_for_each_entry(call, &ftrace_events, list) {
-
-                if (!call->name || !call->regfunc)
-                        continue;
-
-                if (match &&
-                    strcmp(match, call->name) != 0 &&
-                    strcmp(match, call->system) != 0)
-                        continue;
-
-                if (sub && strcmp(sub, call->system) != 0)
-                        continue;
-
-                if (event && strcmp(event, call->name) != 0)
-                        continue;
-
-                ftrace_event_enable_disable(call, set);
-
-                ret = 0;
-        }
-        mutex_unlock(&event_mutex);
-
-        return ret;
+        return __ftrace_set_clr_event(match, sub, event, set);
 }
 
 /* 128 should be much more than enough */
@@ -408,18 +418,14 @@ system_enable_read(struct file *filp, char __user *ubuf, size_t cnt,
         struct ftrace_event_call *call;
         char buf[2];
         int set = -1;
-        int all = 0;
         int ret;
 
-        if (system[0] == '*')
-                all = 1;
-
         mutex_lock(&event_mutex);
         list_for_each_entry(call, &ftrace_events, list) {
                 if (!call->name || !call->regfunc)
                         continue;
 
-                if (!all && strcmp(call->system, system) != 0)
+                if (system && strcmp(call->system, system) != 0)
                         continue;
 
                 /*
@@ -480,7 +486,6 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
 {
         const char *system = filp->private_data;
         unsigned long val;
-        char *command;
         char buf[64];
         ssize_t ret;
 
@@ -500,30 +505,16 @@ system_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
         if (ret < 0)
                 return ret;
 
-        switch (val) {
-        case 0:
-        case 1:
-                break;
-
-        default:
+        if (val != 0 && val != 1)
                 return -EINVAL;
-        }
 
-        /* +3 for the ":*\0" */
-        command = kmalloc(strlen(system)+3, GFP_KERNEL);
-        if (!command)
-                return -ENOMEM;
-        sprintf(command, "%s:*", system);
-
-        ret = ftrace_set_clr_event(command, val);
+        ret = __ftrace_set_clr_event(NULL, system, NULL, val);
         if (ret)
-                goto out_free;
+                goto out;
 
         ret = cnt;
 
- out_free:
-        kfree(command);
-
+out:
         *ppos += cnt;
 
         return ret;
@@ -1181,7 +1172,7 @@ static __init int event_trace_init(void)
                           &ftrace_show_header_fops);
 
         trace_create_file("enable", 0644, d_events,
-                          "*", &ftrace_system_enable_fops);
+                          NULL, &ftrace_system_enable_fops);
 
         for_each_event(call, __start_ftrace_events, __stop_ftrace_events) {
                 /* The linker may leave blanks */
@@ -1259,7 +1250,6 @@ static __init void event_trace_self_tests(void)
 {
         struct ftrace_event_call *call;
         struct event_subsystem *system;
-        char *sysname;
         int ret;
 
         pr_info("Running tests on trace events:\n");
@@ -1305,14 +1295,7 @@ static __init void event_trace_self_tests(void)
 
                 pr_info("Testing event system %s: ", system->name);
 
-                /* ftrace_set_clr_event can modify the name passed in. */
-                sysname = kstrdup(system->name, GFP_KERNEL);
-                if (WARN_ON(!sysname)) {
-                        pr_warning("Can't allocate memory, giving up!\n");
-                        return;
-                }
-                ret = ftrace_set_clr_event(sysname, 1);
-                kfree(sysname);
+                ret = __ftrace_set_clr_event(NULL, system->name, NULL, 1);
                 if (WARN_ON_ONCE(ret)) {
                         pr_warning("error enabling system %s\n",
                                    system->name);
@@ -1321,14 +1304,7 @@ static __init void event_trace_self_tests(void)
 
                 event_test_stuff();
 
-                sysname = kstrdup(system->name, GFP_KERNEL);
-                if (WARN_ON(!sysname)) {
-                        pr_warning("Can't allocate memory, giving up!\n");
-                        return;
-                }
-                ret = ftrace_set_clr_event(sysname, 0);
-                kfree(sysname);
-
+                ret = __ftrace_set_clr_event(NULL, system->name, NULL, 0);
                 if (WARN_ON_ONCE(ret))
                         pr_warning("error disabling system %s\n",
                                    system->name);
@@ -1341,15 +1317,8 @@ static __init void event_trace_self_tests(void)
         pr_info("Running tests on all trace events:\n");
         pr_info("Testing all events: ");
 
-        sysname = kmalloc(4, GFP_KERNEL);
-        if (WARN_ON(!sysname)) {
-                pr_warning("Can't allocate memory, giving up!\n");
-                return;
-        }
-        memcpy(sysname, "*:*", 4);
-        ret = ftrace_set_clr_event(sysname, 1);
+        ret = __ftrace_set_clr_event(NULL, NULL, NULL, 1);
         if (WARN_ON_ONCE(ret)) {
-                kfree(sysname);
                 pr_warning("error enabling all events\n");
                 return;
         }
@@ -1357,10 +1326,7 @@ static __init void event_trace_self_tests(void)
         event_test_stuff();
 
         /* reset sysname */
-        memcpy(sysname, "*:*", 4);
-        ret = ftrace_set_clr_event(sysname, 0);
-        kfree(sysname);
-
+        ret = __ftrace_set_clr_event(NULL, NULL, NULL, 0);
         if (WARN_ON_ONCE(ret)) {
                 pr_warning("error disabling all events\n");
                 return;