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Date: Mon, 11 Dec 2023 12:06:16 -0800
From: John Fastabend <john.fastabend@gmail.com>
To: Yonghong Song <yonghong.song@linux.dev>, 
 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
Message-ID: <65776bb8d03f5_e82d208fb@john.notmuch>
In-Reply-To: <0415f445-4dff-4b64-bd87-f4de08b94bb7@linux.dev>
References: <20231211083447.1921178-1-houtao@huaweicloud.com>
 <0415f445-4dff-4b64-bd87-f4de08b94bb7@linux.dev>
Subject: Re: [PATCH bpf-next v2] bpf: Update the comments in
 maybe_wait_bpf_programs()
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Yonghong Song wrote:
> 
> 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>
> 
> 

Useful info if you are needing this property.

Acked-by: John Fastabend <john.fastabend@gmail.com>