trace: annotate bitfields in struct ring_buffer_event

This gets rid of a heap of false-positive warnings from the tracer
code due to the use of bitfields.

[rebased for mainline inclusion]
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>

2 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index 8670f1575fe1..29f8599e6bea 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -1,6 +1,7 @@
 #ifndef _LINUX_RING_BUFFER_H
 #define _LINUX_RING_BUFFER_H
 
+#include <linux/kmemcheck.h>
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 
@@ -11,7 +12,10 @@ struct ring_buffer_iter;
  * Don't refer to this struct directly, use functions below.
  */
 struct ring_buffer_event {
+        kmemcheck_bitfield_begin(bitfield);
         u32             type_len:5, time_delta:27;
+        kmemcheck_bitfield_end(bitfield);
+
         u32             array[];
 };
 
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 2e642b2b7253..dc4dc70171ce 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -10,6 +10,7 @@
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/hardirq.h>
+#include <linux/kmemcheck.h>
 #include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/mutex.h>
@@ -1270,6 +1271,7 @@ rb_move_tail(struct ring_buffer_per_cpu *cpu_buffer,
         if (tail < BUF_PAGE_SIZE) {
                 /* Mark the rest of the page with padding */
                 event = __rb_page_index(tail_page, tail);
+                kmemcheck_annotate_bitfield(event, bitfield);
                 rb_event_set_padding(event);
         }
 
@@ -1327,6 +1329,7 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
                 return NULL;
 
         event = __rb_page_index(tail_page, tail);
+        kmemcheck_annotate_bitfield(event, bitfield);
         rb_update_event(event, type, length);
 
         /* The passed in type is zero for DATA */