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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Matt Cover <werekraken@gmail.com>
Cc: davem@davemloft.net, ast@kernel.org, daniel@iogearbox.net,
	kafai@fb.com, songliubraving@fb.com, yhs@fb.com,
	Jason Wang <jasowang@redhat.com>,
	Eric Dumazet <edumazet@google.com>,
	Stanislav Fomichev <sdf@google.com>,
	Matthew Cover <matthew.cover@stackpath.com>,
	mail@timurcelik.de, pabeni@redhat.com,
	Nicolas Dichtel <nicolas.dichtel@6wind.com>,
	wangli39@baidu.com, lifei.shirley@bytedance.com,
	tglx@linutronix.de, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [PATCH net-next] tuntap: Fallback to automq on TUNSETSTEERINGEBPF prog negative return
Date: Wed, 25 Sep 2019 06:33:43 -0400	[thread overview]
Message-ID: <20190925063142-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CAGyo_hpCDPmNvTau50XxRVkq1C=Qn7E8cVkE=BZhhiNF6MjqZA@mail.gmail.com>

On Sun, Sep 22, 2019 at 03:46:19PM -0700, Matt Cover wrote:
> Unless of course we can simply state via
> documentation that any negative return
> for which a define doesn't exist is
> undefined behavior. In which case,
> there is no old vs new behavior and
> no need for an ioctl. Simply the
> understanding provided by the
> documentation.

Unfortunately this isn't sufficient: software can easily return a wrong
value by mistake, and become dependent on an undefined behaviour.

-- 
MST

  parent reply	other threads:[~2019-09-25 10:33 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-20 18:58 [PATCH net-next] tuntap: Fallback to automq on TUNSETSTEERINGEBPF prog negative return Matthew Cover
2019-09-20 19:45 ` Matt Cover
2019-09-22 12:37 ` Michael S. Tsirkin
2019-09-22 17:43   ` Matt Cover
2019-09-22 20:35     ` Michael S. Tsirkin
2019-09-22 22:30       ` Matt Cover
2019-09-22 22:46         ` Matt Cover
2019-09-23  0:28           ` Matt Cover
2019-09-25 10:33           ` Michael S. Tsirkin [this message]
2019-09-23  0:51         ` Jason Wang
2019-09-23  1:15           ` Matt Cover
2019-09-23  2:34             ` Jason Wang
2019-09-23  3:18               ` Matt Cover
2019-09-23  5:15                 ` Jason Wang
2019-09-23 16:31                   ` Matt Cover
2019-09-25  4:08                     ` Jason Wang
2019-09-23  0:46     ` Jason Wang
2019-09-23  1:20       ` Matt Cover
2019-09-23  2:32         ` Jason Wang
2019-09-23  3:00           ` Matt Cover
2019-09-23  5:08             ` Jason Wang

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