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References: <20211026203825.2720459-1-eric.dumazet@gmail.com> <20211026203825.2720459-2-eric.dumazet@gmail.com>
In-Reply-To: <20211026203825.2720459-2-eric.dumazet@gmail.com>
From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Tue, 26 Oct 2021 13:43:18 -0700
Message-ID: <CAADnVQKOXXf4vSKYF2+One8PLfva06d4USdTjQj72S7+czhd_Q@mail.gmail.com>
Subject: Re: [PATCH bpf 1/2] bpf: avoid races in __bpf_prog_run() for 32bit arches
To:     Eric Dumazet <eric.dumazet@gmail.com>
Cc:     Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "David S . Miller" <davem@davemloft.net>,
        netdev <netdev@vger.kernel.org>,
        Eric Dumazet <edumazet@google.com>, bpf <bpf@vger.kernel.org>,
        Andrii Nakryiko <andrii@kernel.org>,
        syzbot <syzkaller@googlegroups.com>
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On Tue, Oct 26, 2021 at 1:38 PM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> From: Eric Dumazet <edumazet@google.com>
>
> __bpf_prog_run() can run from non IRQ contexts, meaning
> it could be re entered if interrupted.
>
> This calls for the irq safe variant of u64_stats_update_{begin|end},
> or risk a deadlock.
>
> This patch is a nop on 64bit arches, fortunately.

u64_stats_update_begin_irqsave is a nop. Good!
We just sent the last bpf tree PR for this cycle.
We'll probably take it into bpf-next after CI has a chance to run it.