From: Yonghong Song <yonghong.song@linux.dev>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>, bpf@vger.kernel.org
Cc: David Vernet <void@manifault.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <martin.lau@kernel.org>,
Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH bpf-next v1 1/2] bpf: Transfer RCU lock state between subprog calls
Date: Sun, 4 Feb 2024 19:12:42 -0800 [thread overview]
Message-ID: <091fa367-10fa-4380-a0ee-d63a67192c46@linux.dev> (raw)
In-Reply-To: <20240204230231.1013964-2-memxor@gmail.com>
On 2/4/24 3:02 PM, Kumar Kartikeya Dwivedi wrote:
> Allow transferring an imbalanced RCU lock state between subprog calls
> during verification. This allows patterns where a subprog call returns
> with an RCU lock held, or a subprog call releases an RCU lock held by
> the caller. Currently, the verifier would end up complaining if the RCU
> lock is not released when processing an exit from a subprog, which is
> non-ideal if its execution is supposed to be enclosed in an RCU read
> section of the caller.
>
> Instead, simply only check whether we are processing exit for frame#0
> and do not complain on an active RCU lock otherwise. We only need to
> update the check when processing BPF_EXIT insn, as copy_verifier_state
> is already set up to do the right thing.
>
> Suggested-by: David Vernet <void@manifault.com>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
next prev parent reply other threads:[~2024-02-05 3:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-04 23:02 [PATCH bpf-next v1 0/2] Transfer RCU lock state across subprog calls Kumar Kartikeya Dwivedi
2024-02-04 23:02 ` [PATCH bpf-next v1 1/2] bpf: Transfer RCU lock state between " Kumar Kartikeya Dwivedi
2024-02-05 2:50 ` Yafang Shao
2024-02-05 3:12 ` Yonghong Song [this message]
2024-02-04 23:02 ` [PATCH bpf-next v1 2/2] selftests/bpf: Add tests for RCU lock transfer between subprogs Kumar Kartikeya Dwivedi
2024-02-05 2:54 ` Yafang Shao
2024-02-05 5:34 ` Kumar Kartikeya Dwivedi
2024-02-05 3:13 ` Yonghong Song
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