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From: "Maciej Żenczykowski" <zenczykowski@gmail.com>
To: David Miller <davem@davemloft.net>,
	Lorenzo Colitti <lorenzo@google.com>,
	astrachan@google.com, Greg KH <greg@kroah.com>
Cc: liuhangbin@gmail.com, Linux NetDev <netdev@vger.kernel.org>,
	mateusz.bajorski@nokia.com, dsa@cumulusnetworks.com
Subject: Re: [PATCH net] fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied
Date: Fri, 31 May 2019 18:43:42 -0700	[thread overview]
Message-ID: <CAHo-OozeC3o9avh5kgKpXq1koRH0fVtNRaM9mb=vduYRNX0T7g@mail.gmail.com> (raw)
In-Reply-To: <20190508.093541.1274244477886053907.davem@davemloft.net>

FYI, this userspace visible change in behaviour breaks Android.

We rely on being able to add a rule and either have a dup be created
(in which case we'll remove it later) or have it fail with EEXIST (in
which case we won't remove it later).

Returning 0 makes atomically changing a rule difficult.

Please revert.

On Wed, May 8, 2019 at 9:39 AM David Miller <davem@davemloft.net> wrote:
>
> From: Hangbin Liu <liuhangbin@gmail.com>
> Date: Tue,  7 May 2019 17:11:18 +0800
>
> > With commit 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to
> > fib_nl_newrule") we now able to check if a rule already exists. But this
> > only works with iproute2. For other tools like libnl, NetworkManager,
> > it still could add duplicate rules with only NLM_F_CREATE flag, like
> >
> > [localhost ~ ]# ip rule
> > 0:      from all lookup local
> > 32766:  from all lookup main
> > 32767:  from all lookup default
> > 100000: from 192.168.7.5 lookup 5
> > 100000: from 192.168.7.5 lookup 5
> >
> > As it doesn't make sense to create two duplicate rules, let's just return
> > 0 if the rule exists.
> >
> > Fixes: 153380ec4b9 ("fib_rules: Added NLM_F_EXCL support to fib_nl_newrule")
> > Reported-by: Thomas Haller <thaller@redhat.com>
> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
>
> Applied and queued up for -stable, thanks.

  reply	other threads:[~2019-06-01  1:43 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-07  9:11 [PATCH net] fib_rules: return 0 directly if an exactly same rule exists when NLM_F_EXCL not supplied Hangbin Liu
2019-05-08 16:35 ` David Miller
2019-06-01  1:43   ` Maciej Żenczykowski [this message]
2019-06-01  9:32     ` Greg KH
2019-06-05  1:43     ` Hangbin Liu
2019-06-05  1:47       ` Lorenzo Colitti
2019-06-05  2:15         ` Hangbin Liu
2019-06-05  2:25           ` Lorenzo Colitti
2019-06-05  3:29             ` Hangbin Liu
2019-06-05  3:43               ` Lorenzo Colitti
2019-06-05  4:05                 ` Hangbin Liu
2019-06-05  3:57       ` David Ahern
2019-06-05  4:08         ` Hangbin Liu
2019-06-05  4:58         ` Lorenzo Colitti
2019-06-05 15:33           ` David Ahern
2019-06-06 23:01             ` Maciej Żenczykowski

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