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authorArnd Bergmann <arnd@arndb.de>2016-03-22 14:27:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-03-22 15:36:02 -0700
commit0335695dfa4df01edff5bb102b9a82a0668ee51e (patch)
tree10ce3b97e625726387e5b4f46fe3d34104bafdaf /include/linux/cred.h
parente8de370188d098bb49483c287b44925957c3c9b6 (diff)
cred/userns: define current_user_ns() as a function
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>
Diffstat (limited to 'include/linux/cred.h')
-rw-r--r--include/linux/cred.h5
1 files changed, 4 insertions, 1 deletions
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;
#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