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Date: Mon, 11 Dec 2023 06:58:04 -0800
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Subject: Re: [PATCH bpf-next v2] bpf: Update the comments in
 maybe_wait_bpf_programs()
Content-Language: en-GB
To: Hou Tao <houtao@huaweicloud.com>, bpf@vger.kernel.org
Cc: Martin KaFai Lau <martin.lau@linux.dev>,
 Alexei Starovoitov <alexei.starovoitov@gmail.com>,
 Andrii Nakryiko <andrii@kernel.org>, Song Liu <song@kernel.org>,
 Hao Luo <haoluo@google.com>, Daniel Borkmann <daniel@iogearbox.net>,
 KP Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>,
 Jiri Olsa <jolsa@kernel.org>, John Fastabend <john.fastabend@gmail.com>,
 houtao1@huawei.com
References: <20231211083447.1921178-1-houtao@huaweicloud.com>
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From: Yonghong Song <yonghong.song@linux.dev>
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On 12/11/23 12:34 AM, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
>
> Since commit 638e4b825d52 ("bpf: Allows per-cpu maps and map-in-map in
> sleepable programs"), sleepable BPF program can also use map-in-map, but
> maybe_wait_bpf_programs() doesn't handle it accordingly. The main reason
> is that using synchronize_rcu_tasks_trace() to wait for the completions
> of these sleepable BPF programs may incur a very long delay and
> userspace may think it is hung, so the wait for sleepable BPF programs
> is skipped. Update the comments in maybe_wait_bpf_programs() to reflect
> the reason.
>
> Signed-off-by: Hou Tao <houtao1@huawei.com>

Acked-by: Yonghong Song <yonghong.song@linux.dev>