diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2018-05-30 08:19:22 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-07-03 11:23:07 +0200 |
| commit | 3e4fab744be24bf88dac651c5878c831743c0fbe (patch) | |
| tree | c03dffc553e5efe21e618e5cbf37ff470756ed70 | |
| parent | 95f871342295f2a616fb28d5e0cf72939fe5db5d (diff) | |
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 <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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/compiler.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 5ce911db7d88..4f3dfabb680f 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -113,7 +113,7 @@ 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"))) \ |