branch-check: fix long->int truncation when profiling branches
authorMikulas Patocka <mpatocka@redhat.com>
Wed, 30 May 2018 12:19:22 +0000 (08:19 -0400)
committerSteven Rostedt (VMware) <rostedt@goodmis.org>
Mon, 4 Jun 2018 21:28:20 +0000 (17:28 -0400)
commit2026d35741f2c3ece73c11eb7e4a15d7c2df9ebe
treef05eb8233131e271c1844dd17c8053e450d607b7
parenta9235b544a0ae95fbd56443bdbd251358c7df4c5
branch-check: fix long->int truncation when profiling branches

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>
include/linux/compiler.h