tracing: Change apply_subsystem_event_filter() paths to check file->system == dir

filter_free_subsystem_preds(), filter_free_subsystem_filters() and
replace_system_preds() can simply check file->system->subsystem and
avoid strcmp(call->class->system).

Better yet, we can pass "struct ftrace_subsystem_dir *dir" instead of
event_subsystem and just check file->system == dir.

Thanks to Namhyung Kim who pointed out that replace_system_preds() can
be changed too.

Link: http://lkml.kernel.org/p/20140715184829.GA20516@redhat.com

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 16 insertions, 23 deletions

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 54a125c8467a..c2ef5a5f21da 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -842,17 +842,14 @@ static inline void __remove_filter(struct ftrace_event_file *file)
                 remove_filter_string(file->filter);
 }
 
-static void filter_free_subsystem_preds(struct event_subsystem *system,
+static void filter_free_subsystem_preds(struct ftrace_subsystem_dir *dir,
                                         struct trace_array *tr)
 {
         struct ftrace_event_file *file;
-        struct ftrace_event_call *call;
 
         list_for_each_entry(file, &tr->events, list) {
-                call = file->event_call;
-                if (strcmp(call->class->system, system->name) != 0)
+                if (file->system != dir)
                         continue;
-
                 __remove_filter(file);
         }
 }
@@ -870,15 +867,13 @@ static inline void __free_subsystem_filter(struct ftrace_event_file *file)
         }
 }
 
-static void filter_free_subsystem_filters(struct event_subsystem *system,
+static void filter_free_subsystem_filters(struct ftrace_subsystem_dir *dir,
                                           struct trace_array *tr)
 {
         struct ftrace_event_file *file;
-        struct ftrace_event_call *call;
 
         list_for_each_entry(file, &tr->events, list) {
-                call = file->event_call;
-                if (strcmp(call->class->system, system->name) != 0)
+                if (file->system != dir)
                         continue;
                 __free_subsystem_filter(file);
         }
@@ -1724,13 +1719,12 @@ struct filter_list {
         struct event_filter     *filter;
 };
 
-static int replace_system_preds(struct event_subsystem *system,
+static int replace_system_preds(struct ftrace_subsystem_dir *dir,
                                 struct trace_array *tr,
                                 struct filter_parse_state *ps,
                                 char *filter_string)
 {
         struct ftrace_event_file *file;
-        struct ftrace_event_call *call;
         struct filter_list *filter_item;
         struct filter_list *tmp;
         LIST_HEAD(filter_list);
@@ -1738,15 +1732,15 @@ static int replace_system_preds(struct event_subsystem *system,
         int err;
 
         list_for_each_entry(file, &tr->events, list) {
-                call = file->event_call;
-                if (strcmp(call->class->system, system->name) != 0)
+                if (file->system != dir)
                         continue;
 
                 /*
                  * Try to see if the filter can be applied
                  *  (filter arg is ignored on dry_run)
                  */
-                err = replace_preds(call, NULL, ps, filter_string, true);
+                err = replace_preds(file->event_call, NULL, ps,
+                                        filter_string, true);
                 if (err)
                         event_set_no_set_filter_flag(file);
                 else
@@ -1756,9 +1750,7 @@ static int replace_system_preds(struct event_subsystem *system,
         list_for_each_entry(file, &tr->events, list) {
                 struct event_filter *filter;
 
-                call = file->event_call;
-
-                if (strcmp(call->class->system, system->name) != 0)
+                if (file->system != dir)
                         continue;
 
                 if (event_no_set_filter_flag(file))
@@ -1780,7 +1772,8 @@ static int replace_system_preds(struct event_subsystem *system,
                 if (err)
                         goto fail_mem;
 
-                err = replace_preds(call, filter, ps, filter_string, false);
+                err = replace_preds(file->event_call, filter, ps,
+                                        filter_string, false);
                 if (err) {
                         filter_disable(file);
                         parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
@@ -1928,7 +1921,7 @@ int create_event_filter(struct ftrace_event_call *call,
  * Identical to create_filter() except that it creates a subsystem filter
  * and always remembers @filter_str.
  */
-static int create_system_filter(struct event_subsystem *system,
+static int create_system_filter(struct ftrace_subsystem_dir *dir,
                                 struct trace_array *tr,
                                 char *filter_str, struct event_filter **filterp)
 {
@@ -1938,7 +1931,7 @@ static int create_system_filter(struct event_subsystem *system,
 
         err = create_filter_start(filter_str, true, &ps, &filter);
         if (!err) {
-                err = replace_system_preds(system, tr, ps, filter_str);
+                err = replace_system_preds(dir, tr, ps, filter_str);
                 if (!err) {
                         /* System filters just show a default message */
                         kfree(filter->filter_string);
@@ -2022,18 +2015,18 @@ int apply_subsystem_event_filter(struct ftrace_subsystem_dir *dir,
         }
 
         if (!strcmp(strstrip(filter_string), "0")) {
-                filter_free_subsystem_preds(system, tr);
+                filter_free_subsystem_preds(dir, tr);
                 remove_filter_string(system->filter);
                 filter = system->filter;
                 system->filter = NULL;
                 /* Ensure all filters are no longer used */
                 synchronize_sched();
-                filter_free_subsystem_filters(system, tr);
+                filter_free_subsystem_filters(dir, tr);
                 __free_filter(filter);
                 goto out_unlock;
         }
 
-        err = create_system_filter(system, tr, filter_string, &filter);
+        err = create_system_filter(dir, tr, filter_string, &filter);
         if (filter) {
                 /*
                  * No event actually uses the system filter