diff options
authorArnd Bergmann <arnd@arndb.de>2016-03-22 14:27:11 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-01-12 11:22:50 +0100
commitbecfb50c66cb290f05552cb8c9b46493540a14ed (patch)
parentf5a636fd416f7a5d4452d21178e718fa627ec4c7 (diff)
cred/userns: define current_user_ns() as a function
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 <arnd@arndb.de> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Cc: David Howells <dhowells@redhat.com> Cc: Yaowei Bai <baiyaowei@cmss.chinamobile.com> Cc: James Morris <james.l.morris@oracle.com> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 2654f75a4c46..b20ffe23a09b 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 8d70e1361ecd..257db64562e5 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -377,7 +377,10 @@ extern struct user_namespace init_user_ns;
#define current_user_ns() (current_cred_xxx(user_ns))
-#define current_user_ns() (&init_user_ns)
+static inline struct user_namespace *current_user_ns(void)
+ return &init_user_ns;