tracing/filters: clean up filter_add_subsystem_pred()

Impact: cleanup, memory leak fix

This patch cleans up filter_add_subsystem_pred():

- searches for the field before creating a copy of the pred

- fixes memory leak in the case a predicate isn't applied

- if -ENOMEM, makes sure there's no longer a reference to the
  pred so the caller can free the half-finished filter

- changes the confusing i == MAX_FILTER_PRED - 1 comparison
  previously remarked upon

This affects only per-subsystem event filtering.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237796808.7527.40.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 19f61dd..fdab30d 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -585,6 +585,7 @@ subsystem_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
        }
 
        if (filter_add_subsystem_pred(system, pred)) {
+               filter_free_subsystem_preds(system);
                filter_free_pred(pred);
                return -EINVAL;
        }

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index fd01d80..4117c2e 100644 (file)
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -318,22 +318,39 @@ int filter_add_subsystem_pred(struct event_subsystem *system,
                        system->preds[i] = pred;
                        break;
                }
-               if (i == MAX_FILTER_PRED - 1)
-                       return -EINVAL;
        }
 
+       if (i == MAX_FILTER_PRED)
+               return -EINVAL;
+
        events_for_each(call) {
+               int err;
+
                if (!call->name || !call->regfunc)
                        continue;
 
-               if (!strcmp(call->system, system->name)) {
-                       event_pred = copy_pred(pred);
-                       if (event_pred)
-                               filter_add_pred(call, event_pred);
-               }
+               if (strcmp(call->system, system->name))
+                       continue;
+
+               if (!find_event_field(call, pred->field_name))
+                       continue;
+
+               event_pred = copy_pred(pred);
+               if (!event_pred)
+                       goto oom;
+
+               err = filter_add_pred(call, event_pred);
+               if (err)
+                       filter_free_pred(event_pred);
+               if (err == -ENOMEM)
+                       goto oom;
        }
 
        return 0;
+
+oom:
+       system->preds[i] = NULL;
+       return -ENOMEM;
 }
 
 int filter_parse(char **pbuf, struct filter_pred *pred)