Re: [PATCH net-next 1/3] arm64: bpf: implement bpf_tail_call() helper

[Z Lim <zlim.lnx@gmail.com>]

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Hi Daniel,

On Sun, Jun 5, 2016 at 12:53 AM, Daniel Borkmann <daniel@iogearbox.net> wrote:
> On 06/05/2016 01:46 AM, kbuild test robot wrote:
>>
>> Hi,
>>
>> [auto build test ERROR on net-next/master]
>>
>> url:
>> https://github.com/0day-ci/linux/commits/Zi-Shen-Lim/arm64-bpf-implement-bpf_tail_call-helper/20160605-060435
>> config: arm64-defconfig (attached as .config)
>> compiler: aarch64-linux-gnu-gcc (Debian 5.3.1-8) 5.3.1 20160205
>> reproduce:
>>          wget
>> https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross
>> -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # save the attached .config to linux build tree
>>          make.cross ARCH=arm64
>>
>> All errors (new ones prefixed by >>):
>>
>>     In file included from arch/arm64/net/bpf_jit_comp.c:21:0:
>>     include/linux/bpf.h: In function 'bpf_prog_get':
>>>>
>>>> include/linux/bpf.h:235:9: error: implicit declaration of function
>>>> 'ERR_PTR' [-Werror=implicit-function-declaration]
>>
>>       return ERR_PTR(-EOPNOTSUPP);
>>              ^
>>     include/linux/bpf.h:235:9: warning: return makes pointer from integer
>> without a cast [-Wint-conversion]
>>     In file included from include/linux/rwsem.h:17:0,
>>                      from include/linux/mm_types.h:10,
>>                      from include/linux/sched.h:27,
>>                      from arch/arm64/include/asm/compat.h:25,
>>                      from arch/arm64/include/asm/stat.h:23,
>>                      from include/linux/stat.h:5,
>>                      from include/linux/compat.h:12,
>>                      from include/linux/filter.h:10,
>>                      from arch/arm64/net/bpf_jit_comp.c:22:
>>     include/linux/err.h: At top level:
>>>>
>>>> include/linux/err.h:23:35: error: conflicting types for 'ERR_PTR'
>>
>>      static inline void * __must_check ERR_PTR(long error)
>>                                        ^
>>     In file included from arch/arm64/net/bpf_jit_comp.c:21:0:
>>     include/linux/bpf.h:235:9: note: previous implicit declaration of
>> 'ERR_PTR' was here
>>       return ERR_PTR(-EOPNOTSUPP);
>>              ^
>>     cc1: some warnings being treated as errors
>
>
> Looks like including linux/bpf.h at the very beginning causes issues when
> bpf
> syscall is disabled. We should probably just include linux/err.h from bpf.h.

How about the attached patch? Fixes compilation error on build
!CONFIG_BPF_SYSCALL.

Also, should this patch be sent to net or net-next (along with this series)?

Thanks,
z

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From 0633e3e528e11b09691fbf533ba7fdaf4c52f772 Mon Sep 17 00:00:00 2001
From: Zi Shen Lim <zlim.lnx@gmail.com>
Date: Sun, 5 Jun 2016 21:43:14 -0700
Subject: [PATCH] bpf: fix missing header inclusion

Commit 0fc174dea545 ("ebpf: make internal bpf API independent of
CONFIG_BPF_SYSCALL ifdefs") introduced usage of ERR_PTR() in
bpf_prog_get(), however did not include linux/err.h.

Without this patch, when compiling arm64 BPF without CONFIG_BPF_SYSCALL:
...
In file included from arch/arm64/net/bpf_jit_comp.c:21:0:
include/linux/bpf.h: In function 'bpf_prog_get':
include/linux/bpf.h:235:9: error: implicit declaration of function 'ERR_PTR' [-Werror=implicit-function-declaration]
  return ERR_PTR(-EOPNOTSUPP);
         ^
include/linux/bpf.h:235:9: warning: return makes pointer from integer without a cast [-Wint-conversion]
In file included from include/linux/rwsem.h:17:0,
                 from include/linux/mm_types.h:10,
                 from include/linux/sched.h:27,
                 from arch/arm64/include/asm/compat.h:25,
                 from arch/arm64/include/asm/stat.h:23,
                 from include/linux/stat.h:5,
                 from include/linux/compat.h:12,
                 from include/linux/filter.h:10,
                 from arch/arm64/net/bpf_jit_comp.c:22:
include/linux/err.h: At top level:
include/linux/err.h:23:35: error: conflicting types for 'ERR_PTR'
 static inline void * __must_check ERR_PTR(long error)
                                   ^
In file included from arch/arm64/net/bpf_jit_comp.c:21:0:
include/linux/bpf.h:235:9: note: previous implicit declaration of 'ERR_PTR' was here
  return ERR_PTR(-EOPNOTSUPP);
         ^
...

Fixes: 0fc174dea545 ("ebpf: make internal bpf API independent of CONFIG_BPF_SYSCALL ifdefs")
Suggested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
---
 include/linux/bpf.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 8ee27b8..1bcae82 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -11,6 +11,7 @@
 #include <linux/workqueue.h>
 #include <linux/file.h>
 #include <linux/percpu.h>
+#include <linux/err.h>
 
 struct bpf_map;
 
-- 
1.9.1