Messages in this thread | | | Subject | Re: [PATCH] Fix tun: wake up waitqueues after IFF_UP is set | From | Jason Wang <> | Date | Mon, 17 Jun 2019 16:16:28 +0800 |
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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); >> - 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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