netdev - Re: [PATCH bpf-next 3/4] bpf: Fix net.core.bpf_jit

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Message-ID: <20220309232253.v6oqev7jock7vm7i@ast-mbp.dhcp.thefacebook.com>
Date:   Wed, 9 Mar 2022 15:22:53 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Hou Tao <houtao1@...wei.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>,
        John Fastabend <john.fastabend@...il.com>,
        Yonghong Song <yhs@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        KP Singh <kpsingh@...nel.org>, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next 3/4] bpf: Fix net.core.bpf_jit_harden race

On Wed, Mar 09, 2022 at 08:33:20PM +0800, Hou Tao wrote:
> It is the bpf_jit_harden counterpart to commit 60b58afc96c9 ("bpf: fix
> net.core.bpf_jit_enable race"). bpf_jit_harden will be tested twice
> for each subprog if there are subprogs in bpf program and constant
> blinding may increase the length of program, so when running
> "./test_progs -t subprogs" and toggling bpf_jit_harden between 0 and 2,
> jit_subprogs may fail because constant blinding increases the length
> of subprog instructions during extra passs.
> 
> So cache the value of bpf_jit_blinding_enabled() during program
> allocation, and use the cached value during constant blinding, subprog
> JITing and args tracking of tail call.

Looks like this patch alone is enough.
With race fixed. Patches 1 and 2 are no longer necessary, right?