netdev - Re: [PATCH 1/5] samples/bpf: fix test_lru

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Date:   Wed, 22 May 2019 01:32:57 +0200
From:   Matteo Croce <mcroce@...hat.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        xdp-newbies@...r.kernel.org, bpf@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>
Subject: Re: [PATCH 1/5] samples/bpf: fix test_lru_dist build

On Tue, May 21, 2019 at 7:07 PM Jakub Kicinski
<jakub.kicinski@...ronome.com> wrote:
>
> On Tue, 21 May 2019 17:36:17 +0200, Matteo Croce wrote:
> > On Tue, May 21, 2019 at 5:21 PM Daniel Borkmann <daniel@...earbox.net> wrote:
> > >
> > > On 05/20/2019 10:38 PM, Jakub Kicinski wrote:
> > > > On Mon, 20 May 2019 19:46:27 +0200, Matteo Croce wrote:
> > > >> On Sat, May 18, 2019 at 2:46 AM Matteo Croce <mcroce@...hat.com> wrote:
> > > >>>
> > > >>> Fix the following error by removing a duplicate struct definition:
> > > >>
> > > >> Hi all,
> > > >>
> > > >> I forget to send a cover letter for this series, but basically what I
> > > >> wanted to say is that while patches 1-3 are very straightforward,
> > > >> patches 4-5 are a bit rough and I accept suggstions to make a cleaner
> > > >> work.
> > > >
> > > > samples depend on headers being locally installed:
> > > >
> > > > make headers_install
> > > >
> > > > Are you intending to change that?
> > >
> > > +1, Matteo, could you elaborate?
> > >
> > > On latest bpf tree, everything compiles just fine:
> > >
> > > [root@...ux bpf]# make headers_install
> > > [root@...ux bpf]# make -C samples/bpf/
> > > make: Entering directory '/home/darkstar/trees/bpf/samples/bpf'
> > > make -C ../../ /home/darkstar/trees/bpf/samples/bpf/ BPF_SAMPLES_PATH=/home/darkstar/trees/bpf/samples/bpf
> > > make[1]: Entering directory '/home/darkstar/trees/bpf'
> > >   CALL    scripts/checksyscalls.sh
> > >   CALL    scripts/atomic/check-atomics.sh
> > >   DESCEND  objtool
> > > make -C /home/darkstar/trees/bpf/samples/bpf/../../tools/lib/bpf/ RM='rm -rf' LDFLAGS= srctree=/home/darkstar/trees/bpf/samples/bpf/../../ O=
> > >   HOSTCC  /home/darkstar/trees/bpf/samples/bpf/test_lru_dist
> > >   HOSTCC  /home/darkstar/trees/bpf/samples/bpf/sock_example
> > >
> >
> > Hi all,
> >
> > I have kernel-headers installed from master, but yet the samples fail to build:
> >
> > matteo@...bo:~/src/linux/samples/bpf$ rpm -q kernel-headers
> > kernel-headers-5.2.0_rc1-38.x86_64
> >
> > matteo@...bo:~/src/linux/samples/bpf$ git describe HEAD
> > v5.2-rc1-97-g5bdd9ad875b6
> >
> > matteo@...bo:~/src/linux/samples/bpf$ make
> > make -C ../../ /home/matteo/src/linux/samples/bpf/
> > BPF_SAMPLES_PATH=/home/matteo/src/linux/samples/bpf
> > make[1]: Entering directory '/home/matteo/src/linux'
> >   CALL    scripts/checksyscalls.sh
> >   CALL    scripts/atomic/check-atomics.sh
> >   DESCEND  objtool
> > make -C /home/matteo/src/linux/samples/bpf/../../tools/lib/bpf/ RM='rm
> > -rf' LDFLAGS= srctree=/home/matteo/src/linux/samples/bpf/../../ O=
> >   HOSTCC  /home/matteo/src/linux/samples/bpf/test_lru_dist
> > /home/matteo/src/linux/samples/bpf/test_lru_dist.c:39:8: error:
> > redefinition of ‘struct list_head’
> >    39 | struct list_head {
> >       |        ^~~~~~~~~
> > In file included from /home/matteo/src/linux/samples/bpf/test_lru_dist.c:9:
> > ./tools/include/linux/types.h:69:8: note: originally defined here
> >    69 | struct list_head {
> >       |        ^~~~~~~~~
> > make[2]: *** [scripts/Makefile.host:90:
> > /home/matteo/src/linux/samples/bpf/test_lru_dist] Error 1
> > make[1]: *** [Makefile:1762: /home/matteo/src/linux/samples/bpf/] Error 2
> > make[1]: Leaving directory '/home/matteo/src/linux'
> > make: *** [Makefile:231: all] Error 2
> >
> > Am I missing something obvious?
>
> Yes ;)  Samples use a local installation of headers in $objtree/usr (I
> think, maybe $srctree/usr).  So you need to do make headers_install in
> your kernel source tree, otherwise the include path from tools/ takes
> priority over your global /usr/include and causes these issues.  I had
> this path in my tree for some time, but I don't like enough to post it:
>
> commit 35fb614049e93d46af708c0eaae6601df54017b3
> Author: Jakub Kicinski <jakub.kicinski@...ronome.com>
> Date:   Mon Dec 3 15:00:24 2018 -0800
>
>     bpf: maybe warn ppl about hrds_install
>
>     Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 4f0a1cdbfe7c..f79a4ed2f9f7 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -208,6 +208,15 @@ HOSTCC = $(CROSS_COMPILE)gcc
>  CLANG_ARCH_ARGS = -target $(ARCH)
>  endif
>
> +HDR_PROBE := $(shell echo "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
> +       gcc $(KBUILD_HOSTCFLAGS) -x c - -o /dev/null 2>/dev/null && \
> +       echo okay)
> +
> +ifeq ($(HDR_PROBE),)
> +$(warning Detected possible issues with include path.)
> +$(warning Please install kernel headers locally (make headers_install))
> +endif
> +
>  BTF_LLC_PROBE := $(shell $(LLC) -march=bpf -mattr=help 2>&1 | grep dwarfris)
>  BTF_PAHOLE_PROBE := $(shell $(BTF_PAHOLE) --help 2>&1 | grep BTF)
>  BTF_OBJCOPY_PROBE := $(shell $(LLVM_OBJCOPY) --help 2>&1 | grep -i 'usage.*llvm')

Hi Jakub,

I see now, It worked, thanks. This is a bit error prone IMHO, if you
ever think about sending this patch, consider it ACKed by me.

Thanks,
-- 
Matteo Croce
per aspera ad upstream