From 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@redhat.com>
Date: Wed, 30 May 2018 08:19:22 -0400
Subject: [PATCH] branch-check: fix long->int truncation when profiling
 branches
Git-commit: 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe
Patch-mainline: v4.18-rc1
References: bsc#1101116,fate#324698

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.

Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1805300818140.24812@file01.intranet.prod.int.rdu2.redhat.com

Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Coly Li <colyli@suse.de>
---
 include/linux/compiler.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index ab4711c63601..42506e4d1f53 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -21,7 +21,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #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"))) \
-- 
2.18.0