Re: Add AT_* constants from Linux 6.12

[Nathan Chancellor <nathan@kernel.org>]

On Sun, Aug 03, 2025 at 07:58:53PM +0200, Florian Weimer wrote:
> * Nathan Chancellor:
> 
> > On Mon, Apr 14, 2025 at 01:00:22PM -0300, Adhemerval Zanella Netto wrote:
> >> 
> >> 
> >> On 09/04/25 16:51, Joseph Myers wrote:
> >> > Linux 6.12 adds AT_RENAME_* aliases for RENAME_* flags for renameat2,
> >> > and also AT_HANDLE_MNT_ID_UNIQUE.  Add the first set of aliases to
> >> > stdio.h alongside the RENAME_* names, and AT_HANDLE_MNT_ID_UNIQUE to
> >> > bits/fcntl-linux.h.
> >> > 
> >> > Tested for x86_64.
> >> 
> >> LGTM, although I am not sure about the possible <linux/fcntl.h> inclusion
> >> clash.
> >
> > Yeah, this appears to be the reason I now see some warnings when
> > building samples/vfs/test-statx.c and samples/watch_queue/watch_test.c
> > in the Linux kernel, which includes both linux/fcntl.h and stdio.h:
> >
> >   In file included from samples/vfs/test-statx.c:23:
> >   usr/include/linux/fcntl.h:159:9: warning: 'AT_RENAME_NOREPLACE' macro redefined [-Wmacro-redefined]
> >     159 | #define AT_RENAME_NOREPLACE     0x0001
> >         |         ^
> >   /usr/include/stdio.h:171:10: note: previous definition is here
> >     171 | # define AT_RENAME_NOREPLACE RENAME_NOREPLACE
> >         |          ^
> >   In file included from samples/vfs/test-statx.c:23:
> >   usr/include/linux/fcntl.h:160:9: warning: 'AT_RENAME_EXCHANGE' macro redefined [-Wmacro-redefined]
> >     160 | #define AT_RENAME_EXCHANGE      0x0002
> >         |         ^
> >   /usr/include/stdio.h:173:10: note: previous definition is here
> >     173 | # define AT_RENAME_EXCHANGE RENAME_EXCHANGE
> >         |          ^
> >   In file included from samples/vfs/test-statx.c:23:
> >   usr/include/linux/fcntl.h:161:9: warning: 'AT_RENAME_WHITEOUT' macro redefined [-Wmacro-redefined]
> >     161 | #define AT_RENAME_WHITEOUT      0x0004
> >         |         ^
> >   /usr/include/stdio.h:175:10: note: previous definition is here
> >     175 | # define AT_RENAME_WHITEOUT RENAME_WHITEOUT
> >         |          ^
> >
> > Whose bug is this?
> 
> In glibc, we should use the same token sequence as in the UAPI header.

Is there going to be a patch submitted on the glibc side? I have been
working around this locally in the kernel, should I submit this upstream
since it is in a released glibc?

diff --git a/samples/vfs/test-statx.c b/samples/vfs/test-statx.c
index 49c7a46cee07..17332100a2b5 100644
--- a/samples/vfs/test-statx.c
+++ b/samples/vfs/test-statx.c
@@ -20,6 +20,9 @@
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <linux/stat.h>
+#undef AT_RENAME_NOREPLACE
+#undef AT_RENAME_EXCHANGE
+#undef AT_RENAME_WHITEOUT
 #include <linux/fcntl.h>
 #define statx foo
 #define statx_timestamp foo_timestamp
diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c
index 8c6cb57d5cfc..c3c0111cae40 100644
--- a/samples/watch_queue/watch_test.c
+++ b/samples/watch_queue/watch_test.c
@@ -16,6 +16,9 @@
 #include <errno.h>
 #include <sys/ioctl.h>
 #include <limits.h>
+#undef AT_RENAME_NOREPLACE
+#undef AT_RENAME_EXCHANGE
+#undef AT_RENAME_WHITEOUT
 #include <linux/watch_queue.h>
 #include <linux/unistd.h>
 #include <linux/keyctl.h>