The function __builtin_expect returns long type (see the gcc
documentation), and so do macros likely and unlikely. Unfortunatelly, when
CONFIG_PROFILE_ANNOTATED_BRANCHES is selected, the macros likely and
unlikely expand to __branch_check__ and __branch_check__ truncates the
long type to int. This unintended truncation may cause bugs in various
kernel code (we found a bug in dm-writecache because of it), so it's
better to fix __branch_check__ to return long.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
include/linux/compiler.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/include/linux/compiler.h
===================================================================
--- linux-2.6.orig/include/linux/compiler.h 2018-02-26 20:34:17.000000000 +0100
+++ linux-2.6/include/linux/compiler.h 2018-05-30 14:11:53.000000000 +0200
@@ -21,7 +21,7 @@ void ftrace_likely_update(struct ftrace_
#define unlikely_notrace(x) __builtin_expect(!!(x), 0)
#define __branch_check__(x, expect, is_constant) ({ \
- int ______r; \
+ long ______r; \
static struct ftrace_likely_data \
__attribute__((__aligned__(4))) \
__attribute__((section("_ftrace_annotated_branch"))) \
