netdev - Re: [PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU exceptions cleanup

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Message-ID: <20190225135618.5687e4c2@elisabeth>
Date:   Mon, 25 Feb 2019 13:56:18 +0100
From:   Stefano Brivio <sbrivio@...hat.com>
To:     Sabrina Dubroca <sd@...asysnail.net>,
        Paolo Abeni <pabeni@...hat.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        David Ahern <dsahern@...il.com>
Subject: Re: [PATCH net v2 2/2] selftests: pmtu: add explicit tests for PMTU
 exceptions cleanup

On Mon, 25 Feb 2019 13:33:30 +0100
Sabrina Dubroca <sd@...asysnail.net> wrote:

> 2019-02-25, 12:13:46 +0100, Paolo Abeni wrote:
> > +	if ! timeout 1 ${ns_a} ip link del dev veth_A-R1; then  
> 
> That doesn't work. "ip link del" is stuck in a way that timeout can't
> terminate it, so this is still going to hang. Did you actually test
> this? :/

Indeed, upon actual testing, this hangs and the error is not reported.

> > +		err "  can't delete veth device in a timely
> > manner, PMTU dst likely leaked"
> > +		return 1
> > +	fi
> > +	return 0
> > +}  

You can use a subshell here, something like:

	${ns_a} ip link del dev veth_A-R1 &
	iplink_pid=$!
	sleep 1
	if [ "$(cat /proc/${iplink_pid}/cmdline 2>/dev/null | tr -d '\0')" = "iplinkdeldevveth_A-R1" ]; then
		err "  can't delete veth device in a timely manner, PMTU dst likely leaked"
		return 1
	fi
}

and now that I tried to run as a single test and couldn't find it, I
think it would also be worth it to rename the tests to something more
sensible.

Right now you have test_pmtu_ipv6_exception_cleanup() calling
test_cleanup_...(), I think it's confusing. Just call the test
test_cleanup_ipv6_exception(), it doesn't have so much to do with PMTU
anyway.

-- 
Stefano