netdev - Re: [PATCH bpf-next] libbpf: fix libbpf

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Date:   Mon, 4 Feb 2019 17:51:47 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Yonghong Song <yhs@...com>
Cc:     Stanislav Fomichev <sdf@...gle.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "ast@...nel.org" <ast@...nel.org>,
        "daniel@...earbox.net" <daniel@...earbox.net>
Subject: Re: [PATCH bpf-next] libbpf: fix libbpf_print

On Tue, Feb 05, 2019 at 12:37:29AM +0000, Yonghong Song wrote:
> 
> 
> On 2/4/19 4:20 PM, Stanislav Fomichev wrote:
> > With the recent print rework we now have the following problem:
> > pr_{warning,info,debug} expand to __pr which calls libbpf_print.
> > libbpf_print does va_start and calls __libbpf_pr with va_list argument.
> > In __base_pr we again do va_start. Because the next argument is a
> > va_list, we don't get correct pointer to the argument (and print noting
> > in my case, I don't know why it doesn't crash tbh).
> > 
> > Fix this by changing libbpf_print_fn_t signature to accept va_list and
> > remove unneeded calls to va_start in the existing users.
> > 
> > Alternatively, this can we solved by exporting __libbpf_pr and
> > changing __pr macro to (and killing libbpf_print):
> > {
> > 	if (__libbpf_pr)
> > 		__libbpf_pr(level, "libbpf: " fmt, ##__VA_ARGS__)
> > }
> > 
> > Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
> 
> It is my mistake. My early version did passed correctly and later
> on I made some changes and did not test properly. Thanks for the fix!
> 
> Acked-by: Yonghong Song <yhs@...com>

argh.
Applied. Thanks for the fix.
Yonghong, how was the earlier patch set tested?
It sounds that nothing should have worked.
How perf changes were tested?