tracing/filters: use ring_buffer_discard_commit() in filter_check_discard()

This patch changes filter_check_discard() to make use of the new
ring_buffer_discard_commit() function and modifies the current users to
call the old commit function in the non-discard case.

It also introduces a version of filter_check_discard() that uses the
global trace buffer (filter_current_check_discard()) for those cases.

v2 changes:

- fix compile error noticed by Ingo Molnar

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1239178554.10295.36.camel@tropicana>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/kmemtrace.c b/kernel/trace/kmemtrace.c
index 9419ad1..86cdf67 100644
--- a/kernel/trace/kmemtrace.c
+++ b/kernel/trace/kmemtrace.c
@@ -63,9 +63,8 @@
 	entry->gfp_flags	= gfp_flags;
 	entry->node		= node;
 
-	filter_check_discard(call, entry, event);
-
-	ring_buffer_unlock_commit(tr->buffer, event);
+	if (!filter_check_discard(call, entry, tr->buffer, event))
+		ring_buffer_unlock_commit(tr->buffer, event);
 
 	trace_wake_up();
 }
@@ -90,9 +89,8 @@
 	entry->call_site	= call_site;
 	entry->ptr		= ptr;
 
-	filter_check_discard(call, entry, event);
-
-	ring_buffer_unlock_commit(tr->buffer, event);
+	if (!filter_check_discard(call, entry, tr->buffer, event))
+		ring_buffer_unlock_commit(tr->buffer, event);
 
 	trace_wake_up();
 }