From patchwork Mon Mar 14 23:21:06 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 102573 Delivered-To: patch@linaro.org Received: by 10.112.199.169 with SMTP id jl9csp330263lbc; Mon, 14 Mar 2016 16:22:00 -0700 (PDT) X-Received: by 10.98.9.219 with SMTP id 88mr34445754pfj.0.1457997720715; Mon, 14 Mar 2016 16:22:00 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id hx6si5569077pac.95.2016.03.14.16.22.00; Mon, 14 Mar 2016 16:22:00 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932527AbcCNXV4 (ORCPT + 31 others); Mon, 14 Mar 2016 19:21:56 -0400 Received: from mout.kundenserver.de ([212.227.126.135]:65228 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298AbcCNXVx (ORCPT ); Mon, 14 Mar 2016 19:21:53 -0400 Received: from wuerfel.lan. ([78.42.132.4]) by mrelayeu.kundenserver.de (mreue005) with ESMTPA (Nemesis) id 0MYa6I-1aJ2Yv0RfO-00VTt8; Tue, 15 Mar 2016 00:21:27 +0100 From: Arnd Bergmann To: Tejun Heo , Li Zefan , Johannes Weiner Cc: Arnd Bergmann , Aditya Kali , Aleksa Sarai , cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] cgroup: avoid false positive gcc-6 warning Date: Tue, 15 Mar 2016 00:21:06 +0100 Message-Id: <1457997681-2011105-1-git-send-email-arnd@arndb.de> X-Mailer: git-send-email 2.7.0 X-Provags-ID: V03:K0:xhljZROxHATIIn5Q8DWE4+dE0ZY9qjupnzrUKsQcjD2CYz2RDSq Lg89peDYKZl0dHDHSbo/IqwolDPCWNgKEG1B6RRjF6Tx8nURSd+glSiEbg0l25iSF9TfaUx HKEWZ3QOU/2w6ry4bFYs4El4lkjH0uE8ys7H4VHYeBZPn0xu1DTY/OxS20n5Mbwbnolx0/k 5ZrkoI8szcKJ81bYnCt+Q== X-UI-Out-Filterresults: notjunk:1; V01:K0:PiovSi+iJXo=:QSe+oUZe6SBoIE17pBx98P N0cfEuR82vhWXXhq+8xAyijdKzocXQxIbVB2DHkikvlHwYckqtP0GKUXZZJujLH4uHbgZDHSW gfMywmI771EgW3Nxj13BnNtmaB6Gop/Syd1ch+guBP8rkhYDSydZ/80LSdW2Ov8XLcMibZHr7 8O/RxhZ0HlyxgXf0Kqndju/DiVzQTzjhmbhg1lxs7ovjWtNq22Dqi9hyav9rvZn2yEsiUCKtw JSQ+eqZ8RLlwBan6+45cm8+hkENhnUwfN0ioynAzfxHY8CVatFZQ/NI4oMfKKtmZW99LVXisA mZc3P7P/5hVqQqdVX0J/adclRV/q4tmGvAgUUPMQ3/eHblqOAnmO6WK3ZX4USoHTQDmX599EX jWgDCtaLiduHoNbfRHDdyQptH9+adS14En/snQ/XBjmtIClNjZGKaX9d4lxzmVhl3MHFui4uy F6p1moqoirMyiEQxZpVvDA5pqgZZ/ZOCCNqN7s9xi3eMzVXOMrh+Gd8LtrLgEmcADnGlcPCma RywoPf5VGaK2JSUKycXg3msFcb8IJIwQAzRZJKoJryBKzhPycXCeBuGaGUNRxa36dWnJk4j0b +sEwUmLbDMDLjkuRYoQCpZU9A6nRQQ0KRPUfdFW8KofY3+nZ862SEb3SGaOAVNi33wzM32BlL ofsnafq1v3osHnk2QIRPC+BWL5fH7DyYU6hMSQ0+7gV0o3b7jmTmbN7GBy6xgh+lS68A= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When all subsystems are disabled, gcc notices that cgroup_subsys_enabled_key is a zero-length array and that any access to it must be out of bounds: In file included from ../include/linux/cgroup.h:19:0, from ../kernel/cgroup.c:31: ../kernel/cgroup.c: In function 'cgroup_add_cftypes': ../kernel/cgroup.c:261:53: error: array subscript is above array bounds [-Werror=array-bounds] return static_key_enabled(cgroup_subsys_enabled_key[ssid]); ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ ../include/linux/jump_label.h:271:40: note: in definition of macro 'static_key_enabled' static_key_count((struct static_key *)x) > 0; \ ^ We should never call the function in this particular case, so this is not a bug. In order to silence the warning, this adds an explicit check for the CGROUP_SUBSYS_COUNT==0 case. Signed-off-by: Arnd Bergmann --- v2: use 'false' as the return code instead of '0', as suggested by the friendly kbuild test robot. kernel/cgroup.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.7.0 diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 155c88470543..5f65c1002b4b 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -258,6 +258,9 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css, */ static bool cgroup_ssid_enabled(int ssid) { + if (CGROUP_SUBSYS_COUNT == 0) + return false; + return static_key_enabled(cgroup_subsys_enabled_key[ssid]); }