[PATCH] Linux: Fix enum fsconfig_command detection in <sys/mount.h>

[PATCH] Linux: Fix enum fsconfig_command detection in <sys/mount.h>

[Florian Weimer]

The #ifdef FSOPEN_CLOEXEC check did not work because the macro
was defined prior to its use.  This caused misc/tst-mount to fail
to build with older kernel headers.

Fixes commit 774058d72942249f71d74e7f2b639f77184160a6
("linux: Fix sys/mount.h usage with kernel headers").

Tesed on power64-linux-gnu.

---
 sysdeps/unix/sysv/linux/sys/mount.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/sys/mount.h b/sysdeps/unix/sysv/linux/sys/mount.h
index 2e3fd6a7fe..19841d0738 100644
--- a/sysdeps/unix/sysv/linux/sys/mount.h
+++ b/sysdeps/unix/sysv/linux/sys/mount.h
@@ -188,9 +188,6 @@ enum
 };
 
 
-/* fsopen flags.  */
-#define FSOPEN_CLOEXEC          0x00000001
-
 /* fsmount flags.  */
 #define FSMOUNT_CLOEXEC         0x00000001
 
@@ -261,6 +258,9 @@ enum fsconfig_command
 };
 #endif
 
+/* fsopen flags.  */
+#define FSOPEN_CLOEXEC          0x00000001
+
 /* open_tree flags.  */
 #define OPEN_TREE_CLONE    1         /* Clone the target tree and attach the clone */
 #define OPEN_TREE_CLOEXEC  O_CLOEXEC /* Close the file on execve() */

Re: [PATCH] Linux: Fix enum fsconfig_command detection in <sys/mount.h>

[Andreas Schwab]

On Aug 16 2022, Florian Weimer via Libc-alpha wrote:

> The #ifdef FSOPEN_CLOEXEC check did not work because the macro
> was defined prior to its use.

This is confusing, since generally we want macros to be defined before
their use.  What's important here is that the use is about checking for
absence of the macro in the kernel header.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: [PATCH] Linux: Fix enum fsconfig_command detection in <sys/mount.h>

[Florian Weimer]

* Andreas Schwab:

> On Aug 16 2022, Florian Weimer via Libc-alpha wrote:
>
>> The #ifdef FSOPEN_CLOEXEC check did not work because the macro
>> was defined prior to its use.
>
> This is confusing, since generally we want macros to be defined before
> their use.  What's important here is that the use is about checking for
> absence of the macro in the kernel header.

Do you suggest to reword the commit message?  What about this?

“
The #ifdef FSOPEN_CLOEXEC check did not work because the macro
was always defined in this header prior to the check, so that
the <linux/mount.h> contents did not matter.
”

Thanks,
Florian

Re: [PATCH] Linux: Fix enum fsconfig_command detection in <sys/mount.h>

[Andreas Schwab]

On Aug 16 2022, Florian Weimer wrote:

> “
> The #ifdef FSOPEN_CLOEXEC check did not work because the macro
> was always defined in this header prior to the check, so that
> the <linux/mount.h> contents did not matter.
> ”

WFM.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."