Messages in this thread | | | From | 李菲 <> | Date | Mon, 17 Jun 2019 18:40:34 +0800 | Subject | Re: [External Email] Re: [PATCH] Fix tun: wake up waitqueues after IFF_UP is set |
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Hi all,
On Mon, Jun 17, 2019 at 5:32 PM 李菲 <lifei.shirley@bytedance.com> wrote: > > Ok, thanks for detail suggestion! :) > > On Mon, Jun 17, 2019 at 4:16 PM Jason Wang <jasowang@redhat.com> wrote: >> >> >> On 2019/6/17 下午4:10, Jason Wang wrote: >> > >> > On 2019/6/17 下午3:33, Fei Li wrote: >> >> Currently after setting tap0 link up, the tun code wakes tx/rx waited >> >> queues up in tun_net_open() when .ndo_open() is called, however the >> >> IFF_UP flag has not been set yet. If there's already a wait queue, it >> >> would fail to transmit when checking the IFF_UP flag in tun_sendmsg(). >> >> Then the saving vhost_poll_start() will add the wq into wqh until it >> >> is waken up again. Although this works when IFF_UP flag has been set >> >> when tun_chr_poll detects; this is not true if IFF_UP flag has not >> >> been set at that time. Sadly the latter case is a fatal error, as >> >> the wq will never be waken up in future unless later manually >> >> setting link up on purpose. >> >> >> >> Fix this by moving the wakeup process into the NETDEV_UP event >> >> notifying process, this makes sure IFF_UP has been set before all >> >> waited queues been waken up. >> >> >> Btw, the title needs some tweak. E.g you need use "net" as prefix since >> it's a fix for net.git and "Fix" could be removed like: >> >> [PATCH net] tun: wake up waitqueues after IFF_UP is set. >> >> Thanks >> >> >> >> >> >> Signed-off-by: Fei Li <lifei.shirley@bytedance.com> >> >> --- >> >> drivers/net/tun.c | 17 +++++++++-------- >> >> 1 file changed, 9 insertions(+), 8 deletions(-) >> >> >> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> >> index c452d6d831dd..a3c9cab5a4d0 100644 >> >> --- a/drivers/net/tun.c >> >> +++ b/drivers/net/tun.c >> >> @@ -1015,17 +1015,9 @@ static void tun_net_uninit(struct net_device >> >> *dev) >> >> static int tun_net_open(struct net_device *dev) >> >> { >> >> struct tun_struct *tun = netdev_priv(dev); Will remove the above unused struct in next version. Sorry for the negligence!
Have a nice day, thanks Fei
>> >> - int i; >> >> netif_tx_start_all_queues(dev); >> >> - for (i = 0; i < tun->numqueues; i++) { >> >> - struct tun_file *tfile; >> >> - >> >> - tfile = rtnl_dereference(tun->tfiles[i]); >> >> - tfile->socket.sk->sk_write_space(tfile->socket.sk); >> >> - } >> >> - >> >> return 0; >> >> } >> >> @@ -3634,6 +3626,7 @@ static int tun_device_event(struct >> >> notifier_block *unused, >> >> { >> >> struct net_device *dev = netdev_notifier_info_to_dev(ptr); >> >> struct tun_struct *tun = netdev_priv(dev); >> >> + int i; >> >> if (dev->rtnl_link_ops != &tun_link_ops) >> >> return NOTIFY_DONE; >> >> @@ -3643,6 +3636,14 @@ static int tun_device_event(struct >> >> notifier_block *unused, >> >> if (tun_queue_resize(tun)) >> >> return NOTIFY_BAD; >> >> break; >> >> + case NETDEV_UP: >> >> + for (i = 0; i < tun->numqueues; i++) { >> >> + struct tun_file *tfile; >> >> + >> >> + tfile = rtnl_dereference(tun->tfiles[i]); >> >> + tfile->socket.sk->sk_write_space(tfile->socket.sk); >> >> + } >> >> + break; >> >> default: >> >> break; >> >> } >> > >> > >> > Acked-by: Jason Wang <jasowang@redhat.com) >> >
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