Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752776AbdFSTgz (ORCPT + 2 others); Mon, 19 Jun 2017 15:36:55 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:51891 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752487AbdFSSed (ORCPT ); Mon, 19 Jun 2017 14:34:33 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Arnd Bergmann , David Howells , Yaowei Bai , James Morris , "Paul E. McKenney" , Andrew Morton , Linus Torvalds , Willy Tarreau Subject: [PATCH 3.10 081/268] cred/userns: define current_user_ns() as a function Date: Mon, 19 Jun 2017 20:29:40 +0200 Message-Id: <1497897167-14556-82-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1497897167-14556-1-git-send-email-w@1wt.eu> References: <1497897167-14556-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Arnd Bergmann commit 0335695dfa4df01edff5bb102b9a82a0668ee51e upstream. The current_user_ns() macro currently returns &init_user_ns when user namespaces are disabled, and that causes several warnings when building with gcc-6.0 in code that compares the result of the macro to &init_user_ns itself: fs/xfs/xfs_ioctl.c: In function 'xfs_ioctl_setattr_check_projid': fs/xfs/xfs_ioctl.c:1249:22: error: self-comparison always evaluates to true [-Werror=tautological-compare] if (current_user_ns() == &init_user_ns) This is a legitimate warning in principle, but here it isn't really helpful, so I'm reprasing the definition in a way that shuts up the warning. Apparently gcc only warns when comparing identical literals, but it can figure out that the result of an inline function can be identical to a constant expression in order to optimize a condition yet not warn about the fact that the condition is known at compile time. This is exactly what we want here, and it looks reasonable because we generally prefer inline functions over macros anyway. Signed-off-by: Arnd Bergmann Acked-by: Serge Hallyn Cc: David Howells Cc: Yaowei Bai Cc: James Morris Cc: "Paul E. McKenney" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Willy Tarreau --- include/linux/capability.h | 2 -- include/linux/cred.h | 5 ++++- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/capability.h b/include/linux/capability.h index 9b4378a..eeb43c4 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -40,8 +40,6 @@ struct inode; struct dentry; struct user_namespace; -struct user_namespace *current_user_ns(void); - extern const kernel_cap_t __cap_empty_set; extern const kernel_cap_t __cap_init_eff_set; diff --git a/include/linux/cred.h b/include/linux/cred.h index 6c58dd7..cd3fb73 100644 --- a/include/linux/cred.h +++ b/include/linux/cred.h @@ -345,7 +345,10 @@ extern struct user_namespace init_user_ns; #ifdef CONFIG_USER_NS #define current_user_ns() (current_cred_xxx(user_ns)) #else -#define current_user_ns() (&init_user_ns) +static inline struct user_namespace *current_user_ns(void) +{ + return &init_user_ns; +} #endif -- 2.8.0.rc2.1.gbe9624a