netdev - Re: [PATCH bpf-next] selftests/bpf: make tcp

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Message-ID: <20200311221424.GB2125642@mini-arch.hsd1.ca.comcast.net>
Date:   Wed, 11 Mar 2020 15:14:24 -0700
From:   Stanislav Fomichev <sdf@...ichev.me>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Andrii Nakryiko <andriin@...com>, bpf <bpf@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Stanislav Fomichev <sdf@...gle.com>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next] selftests/bpf: make tcp_rtt test more robust to
 failures

On 03/11, Andrii Nakryiko wrote:
> On Wed, Mar 11, 2020 at 1:41 PM Stanislav Fomichev <sdf@...ichev.me> wrote:
> >
> > On 03/11, Andrii Nakryiko wrote:
> > [..]
> > > +     pthread_join(tid, &server_res);
> > > +     CHECK_FAIL(IS_ERR(server_res));
> >
> > I wonder if we add (move) close(server_fd) before pthread_join(), can we
> > fix this issue without using non-blocking socket? The accept() should
> > return as soon as server_fd is closed so it's essentially your
> > 'server_done'.
> 
> That was my first attempt. Amazingly, closing listening socket FD
> doesn't unblock accept()...
Ugh :-(

In this case, feel free to slap:
Reviewed-by: Stanislav Fomichev <sdf@...gle.com>

My only other (minor) suggestion was to add a small delay in the first
loop:

	while (!server_done) {
		accept()
		if (!err) {
			udelay(50) <--
			continue
		}
	}

But I suppose that shouldn't be that big of a deal..