From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
willemdebruijn.kernel@gmail.com, tom@herbertland.com
Subject: Re: [PATCH net-next V2 3/3] tun: add eBPF based queue selection method
Date: Wed, 1 Nov 2017 21:02:03 +0800 [thread overview]
Message-ID: <43c86606-2911-768d-704f-8b25e04cb47b@redhat.com> (raw)
In-Reply-To: <20171031184002-mutt-send-email-mst@kernel.org>
On 2017年11月01日 00:45, Michael S. Tsirkin wrote:
>> +static void __tun_set_steering_ebpf(struct tun_struct *tun,
>> + struct bpf_prog *new)
>> +{
>> + struct bpf_prog *old;
>> +
>> + old = rtnl_dereference(tun->steering_prog);
>> + rcu_assign_pointer(tun->steering_prog, new);
>> +
>> + if (old) {
>> + synchronize_net();
>> + bpf_prog_destroy(old);
>> + }
>> +}
>> +
> Is this really called under rtnl?
Yes it is __tun_chr_ioctl() will call rtnl_lock().
> If no then rtnl_dereference
> is wrong. If yes I'm not sure you can call synchronize_net
> under rtnl.
>
Are you worrying about the long wait? Looking at synchronize_net(), it does:
void synchronize_net(void)
{
might_sleep();
if (rtnl_is_locked())
synchronize_rcu_expedited();
else
synchronize_rcu();
}
EXPORT_SYMBOL(synchronize_net);
Thanks
next prev parent reply other threads:[~2017-11-01 13:02 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-31 10:32 [PATCH net-next V2 0/3] support changing steering policies in tuntap Jason Wang
2017-10-31 10:32 ` [PATCH net-next V2 1/3] tun: abstract flow steering logic Jason Wang
2017-11-02 1:11 ` Willem de Bruijn
2017-11-02 3:43 ` Jason Wang
2017-11-02 3:45 ` Michael S. Tsirkin
2017-11-02 3:51 ` Jason Wang
2017-11-03 8:49 ` Willem de Bruijn
2017-10-31 10:32 ` [PATCH net-next V2 2/3] tun: introduce ioctls to set and get steering policies Jason Wang
2017-11-02 1:15 ` Willem de Bruijn
2017-10-31 10:32 ` [PATCH net-next V2 3/3] tun: add eBPF based queue selection method Jason Wang
2017-10-31 16:45 ` Michael S. Tsirkin
2017-11-01 13:02 ` Jason Wang [this message]
2017-11-01 13:59 ` Michael S. Tsirkin
2017-11-01 19:12 ` Alexei Starovoitov
2017-11-02 3:24 ` Jason Wang
2017-11-02 3:45 ` Jason Wang
2017-11-03 8:56 ` Willem de Bruijn
2017-11-03 23:56 ` Willem de Bruijn
2017-11-08 5:28 ` Jason Wang
2017-11-08 5:43 ` Michael S. Tsirkin
2017-11-08 11:13 ` Jason Wang
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