From: Mikulas Patocka Date: Wed, 30 May 2018 12:19:22 +0000 (-0400) Subject: branch-check: fix long->int truncation when profiling branches X-Git-Tag: v3.18.114~32 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=291c3c760954281418000ce1aaf59924bb73cf14;p=thirdparty%2Fkernel%2Fstable.git branch-check: fix long->int truncation when profiling branches commit 2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe upstream. 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 Cc: stable@vger.kernel.org Fixes: 1f0d69a9fc815 ("tracing: profile likely and unlikely annotations") Signed-off-by: Mikulas Patocka Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 1a6f01df1496c..8cf7a33e1b72f 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -105,7 +105,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); #define unlikely_notrace(x) __builtin_expect(!!(x), 0) #define __branch_check__(x, expect) ({ \ - int ______r; \ + long ______r; \ static struct ftrace_branch_data \ __attribute__((__aligned__(4))) \ __attribute__((section("_ftrace_annotated_branch"))) \