tracing: Add generic event-name based remove event method

Add a generic method to remove event from dynamic event
list. This is same as other system under ftrace. You
just need to pass the event name with '!', e.g.

  # echo p:new_grp/new_event _do_fork > dynamic_events

This creates an event, and

  # echo '!p:new_grp/new_event _do_fork' > dynamic_events

Or,

  # echo '!p:new_grp/new_event' > dynamic_events

will remove new_grp/new_event event.

Note that this doesn't check the event prefix (e.g. "p:")
strictly, because the "group/event" name must be unique.

Link: http://lkml.kernel.org/r/154140869774.17322.8887303560398645347.stgit@devbox
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Tested-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_dynevent.c b/kernel/trace/trace_dynevent.c
index f17a887abb6696192d3525d8cff8ae9b841af297..dd1f43588d7097a62a84966d8a90b425fd0f2f64 100644 (file)
--- a/kernel/trace/trace_dynevent.c
+++ b/kernel/trace/trace_dynevent.c
@@ -37,10 +37,17 @@ int dyn_event_release(int argc, char **argv, struct dyn_event_operations *type)
        char *system = NULL, *event, *p;
        int ret = -ENOENT;
 
-       if (argv[0][1] != ':')
-               return -EINVAL;
+       if (argv[0][0] == '-') {
+               if (argv[0][1] != ':')
+                       return -EINVAL;
+               event = &argv[0][2];
+       } else {
+               event = strchr(argv[0], ':');
+               if (!event)
+                       return -EINVAL;
+               event++;
+       }
 
-       event = &argv[0][2];
        p = strchr(event, '/');
        if (p) {
                system = event;
@@ -69,7 +76,7 @@ static int create_dyn_event(int argc, char **argv)
        struct dyn_event_operations *ops;
        int ret;
 
-       if (argv[0][0] == '-')
+       if (argv[0][0] == '-' || argv[0][0] == '!')
                return dyn_event_release(argc, argv, NULL);
 
        mutex_lock(&dyn_event_ops_mutex);