Re: [PATCH] sample/bpf: Make perf_event_read() static

From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@fb.com>, Wang Nan <wangnan0@huawei.com>,
	Joe Stringer <joe@ovn.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sample/bpf: Make perf_event_read() static
Date: Thu, 15 Dec 2016 12:54:34 -0300	[thread overview]
Message-ID: <20161215155434.GF6866@kernel.org> (raw)
In-Reply-To: <5852BB73.3080600@iogearbox.net>

Em Thu, Dec 15, 2016 at 04:49:07PM +0100, Daniel Borkmann escreveu:
> On 12/15/2016 04:29 PM, Arnaldo Carvalho de Melo wrote:
> > 
> > While testing Joe's conversion of samples/bpf/ to use tools/lib/bpf/ I
> > noticed some warnings, do you guys mind if I put patches like the one
> > below in my tree, pushing to Ingo soon?
> > 
> > Or is there anything subtle against doing so?
> 
> Fwiw, no objections from my side, there is currently nothing in
> net/net-next tree that could cause conflicts regarding the below
> change, so should be good to take this route instead.

Thanks a lot! 

Ah, since it seems the overhead of having clang/llvm/bc/findutils in
addition to what I have in the containers for distros with suitable
packages is small, I'll probably end up building samples/bpf/ in those
containers, in addition to building perf with/without libelf and
objtool.

This way I'll catch build problems everytime I prepare my pull reqs to
Ingo and hopefully fix them then.

- Arnaldo

> > ----
> > 
> > While building samples/bpf/ on a Fedora Rawhide container, with
> > clang/llvm 3.9 I noticed this:
> > 
> > root@1e797fdfbf4f linux]# make -j4 O=/tmp/build/linux/ samples/bpf/
> > make[1]: Entering directory '/tmp/build/linux'
> >    CHK     include/config/kernel.release
> >    GEN     ./Makefile
> >    CHK     include/generated/uapi/linux/version.h
> >    Using /git/linux as source for kernel
> > <SNIP>
> >    HOSTCC  samples/bpf/trace_output_user.o
> > /git/linux/samples/bpf/trace_output_user.c:64:6: warning: no previous
> > prototype for 'perf_event_read' [-Wmissing-prototypes]
> >   void perf_event_read(print_fn fn)
> >        ^~~~~~~~~~~~~~~
> >    HOSTLD  samples/bpf/trace_output
> > make[1]: Leaving directory '/tmp/build/linux'
> > 
> > Shutup the compiler by setting that function as static.
> > 
> > Cc: Alexei Starovoitov <ast@fb.com>
> > Cc: Daniel Borkmann <daniel@iogearbox.net>
> > Cc: Wang Nan <wangnan0@huawei.com>,
> > Cc: Joe Stringer <joe@ovn.org>
> > Link: http://lkml.kernel.org/n/tip-2wkr4ymwhdie0stbkbiyplt5@git.kernel.org
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> Acked-by: Daniel Borkmann <daniel@iogearbox.net>
> 
> Thanks,
> Daniel