[PATCH 2/2] tracing: Fix event trigger to accept redundant spaces

[Masami Hiramatsu]

Fix the event trigger to accept redundant spaces in
the trigger input.

For example, these return -EINVAL

echo " traceon" > events/ftrace/print/trigger
echo "traceon  if common_pid == 0" > events/ftrace/print/trigger
echo "disable_event:kmem:kmalloc " > events/ftrace/print/trigger

But these are hard to find what is wrong.

To fix this issue, use skip_spaces() to remove spaces
in front of actual tokens, and set NULL if there is no
token.

Fixes: 85f2b08268c0 ("tracing: Add basic event trigger framework")
Cc: sta...@vger.kernel.org
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
 kernel/trace/trace_events_trigger.c |   21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_events_trigger.c 
b/kernel/trace/trace_events_trigger.c
index 3a74736da363..f725802160c0 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -216,11 +216,17 @@ static int event_trigger_regex_open(struct inode *inode, 
struct file *file)
 
 int trigger_process_regex(struct trace_event_file *file, char *buff)
 {
-       char *command, *next = buff;
+       char *command, *next;
        struct event_command *p;
        int ret = -EINVAL;
 
+       next = buff = skip_spaces(buff);
        command = strsep(&next, ": \t");
+       if (next) {
+               next = skip_spaces(next);
+               if (!*next)
+                       next = NULL;
+       }
        command = (command[0] != '!') ? command : command + 1;
 
        mutex_lock(&trigger_cmd_mutex);
@@ -630,8 +636,14 @@ event_trigger_callback(struct event_command *cmd_ops,
        int ret;
 
        /* separate the trigger from the filter (t:n [if filter]) */
-       if (param && isdigit(param[0]))
+       if (param && isdigit(param[0])) {
                trigger = strsep(&param, " \t");
+               if (param) {
+                       param = skip_spaces(param);
+                       if (!*param)
+                               param = NULL;
+               }
+       }
 
        trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);
 
@@ -1368,6 +1380,11 @@ int event_enable_trigger_func(struct event_command 
*cmd_ops,
        trigger = strsep(&param, " \t");
        if (!trigger)
                return -EINVAL;
+       if (param) {
+               param = skip_spaces(param);
+               if (!*param)
+                       param = NULL;
+       }
 
        system = strsep(&trigger, ":");
        if (!trigger)