]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/commit
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)
committerKleber Sacilotto de Souza <kleber.souza@canonical.com>
Mon, 14 Jan 2019 09:28:55 +0000 (09:28 +0000)
commitcf5dab54d32806ed6ae1c7b4040483b0805c8da9
tree6aab8defaf35863677fa9acc1f40ac5b4124de5b
parentdbfe9df755ed81111f706ec6778f2336ee583de5
branch-check: fix long->int truncation when profiling branches

BugLink: http://bugs.launchpad.net/bugs/1807469
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
include/linux/compiler.h