2021-01-06 16:03:33

by Alan Maguire

Subject: [PATCH bpf] bpftool: fix compilation failure for net.o with older glibc

For older glibc ~2.17, #include'ing both linux/if.h and net/if.h
fails due to complaints about redefinition of interface flags:

CC net.o
In file included from net.c:13:0:
/usr/include/linux/if.h:71:2: error: redeclaration of enumerator ‘IFF_UP’
IFF_UP = 1<<0, /* sysfs */
^
/usr/include/net/if.h:44:5: note: previous definition of ‘IFF_UP’ was here
IFF_UP = 0x1, /* Interface is up. */

The issue was fixed in kernel headers in [1], but since compilation
of net.c picks up system headers the problem can recur.

Dropping #include <linux/if.h> resolves the issue and it is
not needed for compilation anyhow.

[1] https://lore.kernel.org/netdev/1461512707-23058-1-git-send-email-mikko.rapeli__34748.27880641$1462831734$gmane$org@iki.fi/

Fixes: f6f3bac08ff9 ("tools/bpf: bpftool: add net support")
Signed-off-by: Alan Maguire <[email protected]>
---
tools/bpf/bpftool/net.c | 1 -
1 file changed, 1 deletion(-)

diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
index 3fae61e..ff3aa0c 100644
--- a/tools/bpf/bpftool/net.c
+++ b/tools/bpf/bpftool/net.c
@@ -11,7 +11,6 @@
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <net/if.h>
-#include <linux/if.h>
#include <linux/rtnetlink.h>
#include <linux/socket.h>
#include <linux/tc_act/tc_bpf.h>
--
1.8.3.1

2021-01-06 21:42:39

by Martin KaFai Lau

Subject: Re: [PATCH bpf] bpftool: fix compilation failure for net.o with older glibc

On Wed, Jan 06, 2021 at 03:59:06PM +0000, Alan Maguire wrote:
> For older glibc ~2.17, #include'ing both linux/if.h and net/if.h
> fails due to complaints about redefinition of interface flags:
>
> CC net.o
> In file included from net.c:13:0:
> /usr/include/linux/if.h:71:2: error: redeclaration of enumerator ‘IFF_UP’
> IFF_UP = 1<<0, /* sysfs */
> ^
> /usr/include/net/if.h:44:5: note: previous definition of ‘IFF_UP’ was here
> IFF_UP = 0x1, /* Interface is up. */
>
> The issue was fixed in kernel headers in [1], but since compilation
> of net.c picks up system headers the problem can recur.
>
> Dropping #include <linux/if.h> resolves the issue and it is
> not needed for compilation anyhow.
Acked-by: Martin KaFai Lau <[email protected]>

2021-01-06 23:33:17

by patchwork-bot+netdevbpf

Subject: Re: [PATCH bpf] bpftool: fix compilation failure for net.o with older glibc

Hello:

This patch was applied to bpf/bpf.git (refs/heads/master):

On Wed, 6 Jan 2021 15:59:06 +0000 you wrote:
> For older glibc ~2.17, #include'ing both linux/if.h and net/if.h
> fails due to complaints about redefinition of interface flags:
>
> CC net.o
> In file included from net.c:13:0:
> /usr/include/linux/if.h:71:2: error: redeclaration of enumerator ‘IFF_UP’
> IFF_UP = 1<<0, /* sysfs */
> ^
> /usr/include/net/if.h:44:5: note: previous definition of ‘IFF_UP’ was here
> IFF_UP = 0x1, /* Interface is up. */
>
> [...]

Here is the summary with links:
- [bpf] bpftool: fix compilation failure for net.o with older glibc
https://git.kernel.org/bpf/bpf/c/6f02b540d759

You are awesome, thank you!
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