netdev - Re: [PATCH v2 bpf-next] bpf: fix bpf

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Message-ID: <CAADnVQLYt--n_Yp1_A8BVp-p17ymVkkqtzgisKm1a0JGwkhpCw@mail.gmail.com>
Date:   Thu, 14 May 2020 18:38:38 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Kernel Team <kernel-team@...com>, Yonghong Song <yhs@...com>
Subject: Re: [PATCH v2 bpf-next] bpf: fix bpf_iter's task iterator logic

On Wed, May 13, 2020 at 10:54 PM Andrii Nakryiko <andriin@...com> wrote:
>
> task_seq_get_next might stop prematurely if get_pid_task() fails to get
> task_struct. Failure to do so doesn't mean that there are no more tasks with
> higher pids. Procfs's iteration algorithm (see next_tgid in fs/proc/base.c)
> does a retry in such case. After this fix, instead of stopping prematurely
> after about 300 tasks on my server, bpf_iter program now returns >4000, which
> sounds much closer to reality.
>
> Cc: Yonghong Song <yhs@...com>
> Fixes: eaaacd23910f ("bpf: Add task and task/file iterator targets")
> Acked-by: Yonghong Song <yhs@...com>
> Signed-off-by: Andrii Nakryiko <andriin@...com>

Applied. Thanks