Subject: Re: [PATCH] devlink: fix libc and kernel headers collision

From: Baruch Siach <[email-masked]>
Date: Tue, 04 Jun 2019 20:47:50 +0300

Hi Stephen,

On Tue, Jun 04 2019, Stephen Hemminger wrote:
> On Thu, 30 May 2019 18:32:27 +0300
> Baruch Siach <[email-masked]> wrote:
>
>> Since commit 2f1242efe9d ("devlink: Add devlink health show command") we
>> use the sys/sysinfo.h header for the sysinfo(2) system call. But since
>> iproute2 carries a local version of the kernel struct sysinfo, this
>> causes a collision with libc that do not rely on kernel defined sysinfo
>> like musl libc:
>> 
>> In file included from devlink.c:25:0:
>> .../sysroot/usr/include/sys/sysinfo.h:10:8: error: redefinition of 'struct sysinfo'
>>  struct sysinfo {
>>         ^~~~~~~
>> In file included from ../include/uapi/linux/kernel.h:5:0,
>>                  from ../include/uapi/linux/netlink.h:5,
>>                  from ../include/uapi/linux/genetlink.h:6,
>>                  from devlink.c:21:
>> ../include/uapi/linux/sysinfo.h:8:8: note: originally defined here
>>  struct sysinfo {
>> 		^~~~~~~
>> 
>> Rely on the kernel header alone to avoid kernel and userspace headers
>> collision of definitions.
>> 
>> Cc: Aya Levin <[email-masked]>
>> Cc: Moshe Shemesh <[email-masked]>
>> Signed-off-by: Baruch Siach <[email-masked]>
>
> Sorry this breaks the glibc build.
>
>
>     CC       devlink.o
> devlink.c: In function ‘format_logtime’:
> devlink.c:6124:8: warning: implicit declaration of function ‘sysinfo’; did you mean ‘psiginfo’? [-Wimplicit-function-declaration]
>   err = sysinfo(&s_info);
>         ^~~~~~~
>         psiginfo
>
> I backed out the patch now (before pushing it).
> Please fix and resubmit.

I can't think of anything better than this ugly fix:

diff --git a/devlink/devlink.c b/devlink/devlink.c
index 436935f88bda..02e648ef64b3 100644
--- a/devlink/devlink.c
+++ b/devlink/devlink.c
@@ -18,11 +18,12 @@
 #include <limits.h>
 #include <errno.h>
 #include <inttypes.h>
+#include <sys/sysinfo.h>
+#define _LINUX_SYSINFO_H
 #include <linux/genetlink.h>
 #include <linux/devlink.h>
 #include <libmnl/libmnl.h>
 #include <netinet/ether.h>
-#include <sys/sysinfo.h>
 #include <sys/queue.h>
 
 #include "SNAPSHOT.h"

Would that be acceptable?

baruch

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