parse-events: Let function handlers be overridden

Now that plugins are in both system and user directories, the user directory
is processed after the system directory. This makes it highly likely that
a function handler may be added again. Instead of warning about it and failing
let the new function handler override the previous one.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 25 insertions, 2 deletions

diff --git a/parse-events.c b/parse-events.c
index 3c2e9a0..3eb6cb1 100644
--- a/parse-events.c
+++ b/parse-events.c
@@ -79,6 +79,8 @@ static unsigned long long
 process_defined_func(struct trace_seq *s, void *data, int size,
                      struct event_format *event, struct print_arg *arg);
 
+static void free_func_handle(struct pevent_function_handler *func);
+
 /**
  * pevent_buffer_init - init buffer for parsing
  * @buf: buffer to parse
@@ -2254,6 +2256,22 @@ find_func_handler(struct pevent *pevent, char *func_name)
         return func;
 }
 
+static void remove_func_handler(struct pevent *pevent, char *func_name)
+{
+        struct pevent_function_handler *func;
+        struct pevent_function_handler **next;
+
+        next = &pevent->func_handlers;
+        while ((func = *next)) {
+                if (strcmp(func->name, func_name) == 0) {
+                        *next = func->next;
+                        free_func_handle(func);
+                        break;
+                }
+                next = &func->next;
+        }
+}
+
 static enum event_type
 process_func_handler(struct event_format *event, struct pevent_function_handler *func,
                      struct print_arg *arg, char **tok)
@@ -4246,8 +4264,13 @@ int pevent_register_print_function(struct pevent *pevent,
 
         func_handle = find_func_handler(pevent, name);
         if (func_handle) {
-                warning("function helper '%s' already defined", name);
-                return -1;
+                /*
+                 * This is most like caused by the users own
+                 * plugins updating the function. This overrides the
+                 * system defaults.
+                 */
+                pr_stat("override of function helper '%s'", name);
+                remove_func_handler(pevent, name);
         }
 
         func_handle = malloc_or_die(sizeof(*func_handle));