netdev - Re: [PATCH bpf-next v5 07/11] af_unix: implement unix_dgram_bpf

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Date:   Mon, 19 Jul 2021 17:03:15 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        bpf <bpf@...r.kernel.org>, Cong Wang <cong.wang@...edance.com>,
        John Fastabend <john.fastabend@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Lorenz Bauer <lmb@...udflare.com>
Subject: Re: [PATCH bpf-next v5 07/11] af_unix: implement unix_dgram_bpf_recvmsg()

On Sun, Jul 18, 2021 at 10:49 AM Eric Dumazet <eric.dumazet@...il.com> wrote:
>
>
>
> On 7/4/21 9:02 PM, Cong Wang wrote:
> > From: Cong Wang <cong.wang@...edance.com>
> > +     mutex_lock(&u->iolock);
>
> u->iolock mutex is owned here.
>
> > +     if (!skb_queue_empty(&sk->sk_receive_queue) &&
> > +         sk_psock_queue_empty(psock)) {
> > +             ret = __unix_dgram_recvmsg(sk, msg, len, flags);
>
> But __unix_dgram_recvmsg() will also try to grab this mutex ?

Good catch. I should release the lock before calling it. I will send
a patch.

Thanks.