Messages in this thread | | | From | 李菲 <> | Date | Mon, 17 Jun 2019 17:58:38 +0800 | Subject | Re: [External Email] Re: [PATCH] Fix tun: wake up waitqueues after IFF_UP is set |
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Ok, thanks for the 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); > >> - 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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