On Tuesday, January 15, 2013 06:48:08 PM Michael S. Tsirkin wrote:
> On Tue, Jan 15, 2013 at 06:28:46PM +0800, Jason Wang wrote:
> > We forbid polling, writing and reading when the file were detached, this
> > may complex the user in several cases:
> >
> > - when guest pass some buffers to vhost/qemu and then disable some queues,
> >
> > vhost/qemu needs to to its own cleanup which is complex. We can do this
> > simply by allowing a user can still write to an disabled queue to
> > handle this. And user can still do read but just nothing returned.
> >
> > - align the polling behavior with macvtap which never fails when the queue
> > is>
> > created. this can simplify the polling errors handling of its user (e.g
> > vhost)>
> > Signed-off-by: Jason Wang <jasow...@redhat.com>
> > ---
> >
> > drivers/net/tun.c | 18 +++++++++++-------
> > 1 files changed, 11 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> > index af372d0..eb68937 100644
> > --- a/drivers/net/tun.c
> > +++ b/drivers/net/tun.c
> > @@ -307,7 +307,7 @@ static void tun_flow_update(struct tun_struct *tun,
> > u32 rxhash,>
> > rcu_read_lock();
> >
> > - if (tun->numqueues == 1)
> > + if (tun->numqueues == 1 || queue_index >= tun->numqueues)
> >
> > goto unlock;
> >
> > e = tun_flow_find(head, rxhash);
>
> Hmm I don't understand - does something ensure that queue_index is >
> numqueues if the queue is disabled?
I miss this, something is needed.
> Can we check tun->disabled and skip tun_flow_update completely?
> We might need to switch to rcu_assign for tun->disabled for this
> but otherwise it looks easy.
Correct, will post another version, thanks.
>
> > @@ -406,21 +406,21 @@ static void __tun_detach(struct tun_file *tfile,
> > bool clean)>
> > tun = rtnl_dereference(tfile->tun);
> >
> > - if (tun) {
> > + if (tun && !tfile->detached) {
> >
> > u16 index = tfile->queue_index;
> > BUG_ON(index >= tun->numqueues);
> > dev = tun->dev;
> >
> > rcu_assign_pointer(tun->tfiles[index],
> >
> > tun->tfiles[tun->numqueues - 1]);
> >
> > - rcu_assign_pointer(tfile->tun, NULL);
> >
> > ntfile = rtnl_dereference(tun->tfiles[index]);
> > ntfile->queue_index = index;
> >
> > --tun->numqueues;
> >
> > - if (clean)
> > + if (clean) {
> > + rcu_assign_pointer(tfile->tun, NULL);
> >
> > sock_put(&tfile->sk);
> >
> > - else
> > + } else
> >
> > tun_disable_queue(tun, tfile);
> >
> > synchronize_net();
> >
> > @@ -465,6 +465,10 @@ static void tun_detach_all(struct net_device *dev)
> >
> > rcu_assign_pointer(tfile->tun, NULL);
> > --tun->numqueues;
> >
> > }
> >
> > + list_for_each_entry(tfile, &tun->disabled, next) {
> > + wake_up_all(&tfile->wq.wait);
> > + rcu_assign_pointer(tfile->tun, NULL);
> > + }
> >
> > BUG_ON(tun->numqueues != 0);
> >
> > synchronize_net();
> >
> > @@ -491,7 +495,7 @@ static int tun_attach(struct tun_struct *tun, struct
> > file *file)>
> > int err;
> >
> > err = -EINVAL;
> >
> > - if (rtnl_dereference(tfile->tun))
> > + if (rtnl_dereference(tfile->tun) && !tfile->detached)
> >
> > goto out;
> >
> > err = -EBUSY;
> >
> > @@ -1795,7 +1799,7 @@ static int tun_set_queue(struct file *file, struct
> > ifreq *ifr)>
> > ret = tun_attach(tun, file);
> >
> > } else if (ifr->ifr_flags & IFF_DETACH_QUEUE) {
> >
> > tun = rtnl_dereference(tfile->tun);
> >
> > - if (!tun || !(tun->flags & TUN_TAP_MQ))
> > + if (!tun || !(tun->flags & TUN_TAP_MQ) || tfile->detached)
> >
> > ret = -EINVAL;
> >
> > else
> >
> > __tun_detach(tfile, false);
>
> --
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