netdev - Re: [PATCH v6 bpf-next 0/9] bpf: implement variadic printk helper

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Message-ID: <CAADnVQKZ0Wqz-DGwghk1UfrNXCZkoM0n5fLgx1MvC-=OdYUmBg@mail.gmail.com>
Date:   Fri, 17 Sep 2021 14:06:09 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Dave Marchevsky <davemarchevsky@...com>
Cc:     bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Yonghong Song <yhs@...com>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH v6 bpf-next 0/9] bpf: implement variadic printk helper

On Fri, Sep 17, 2021 at 11:29 AM Dave Marchevsky <davemarchevsky@...com> wrote:
>
> This series introduces a new helper, bpf_trace_vprintk, which functions
> like bpf_trace_printk but supports > 3 arguments via a pseudo-vararg u64
> array. The bpf_printk libbpf convenience macro is modified to use
> bpf_trace_vprintk when > 3 varargs are passed, otherwise the previous
> behavior - using bpf_trace_printk - is retained.
>
> Helper functions and macros added during the implementation of
> bpf_seq_printf and bpf_snprintf do most of the heavy lifting for
> bpf_trace_vprintk. There's no novel format string wrangling here.
>
> Usecase here is straightforward: Giving BPF program writers a more
> powerful printk will ease development of BPF programs, particularly
> during debugging and testing, where printk tends to be used.
>
> This feature was proposed by Andrii in libbpf mirror's issue tracker
> [1].
>
> [1] https://github.com/libbpf/libbpf/issues/315
>
> v5 -> v6: Rebase to pick up newly-added helper

Applied. Thanks!