Hi Stefano, On Thu, Mar 10, 2022 at 5:59 PM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: > > Hi Jiyong, > > On Thu, Mar 10, 2022 at 05:18:54PM +0900, Jiyong Park wrote: > >Filtering non-h2g connections out when determining orphaned connections. > >Otherwise, in a nested VM configuration, destroying the nested VM (which > >often involves the closing of /dev/vhost-vsock if there was h2g > >connections to the nested VM) kills not only the h2g connections, but > >also all existing g2h connections to the (outmost) host which are > >totally unrelated. > > > >Tested: Executed the following steps on Cuttlefish (Android running on a > >VM) [1]: (1) Enter into an `adb shell` session - to have a g2h > >connection inside the VM, (2) open and then close /dev/vhost-vsock by > >`exec 3< /dev/vhost-vsock && exec 3<&-`, (3) observe that the adb > >session is not reset. > > > >[1] https://android.googlesource.com/device/google/cuttlefish/ > > > >Signed-off-by: Jiyong Park <jiyong@xxxxxxxxxx> > >--- > > drivers/vhost/vsock.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > >diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c > >index 37f0b4274113..2f6d5d66f5ed 100644 > >--- a/drivers/vhost/vsock.c > >+++ b/drivers/vhost/vsock.c > >@@ -722,6 +722,10 @@ static void vhost_vsock_reset_orphans(struct sock *sk) > > * executing. > > */ > > > >+ /* Only the h2g connections are reset */ > >+ if (vsk->transport != &vhost_transport.transport) > >+ return; > >+ > > /* If the peer is still valid, no need to reset connection */ > > if (vhost_vsock_get(vsk->remote_addr.svm_cid)) > > return; > >-- > >2.35.1.723.g4982287a31-goog > > > > Thanks for your patch! > > Yes, I see the problem and I think I introduced it with the > multi-transports support (ooops). > > So we should add this fixes tag: > > Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") > > > IIUC the problem is for all transports that should only cycle on their > own sockets. Indeed I think there is the same problem if the g2h driver > will be unloaded (or a reset event is received after a VM migration), it > will close all sockets of the nested h2g. > > So I suggest a more generic solution, modifying > vsock_for_each_connected_socket() like this (not tested): > > diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c > index 38baeb189d4e..f04abf662ec6 100644 > --- a/net/vmw_vsock/af_vsock.c > +++ b/net/vmw_vsock/af_vsock.c > @@ -334,7 +334,8 @@ void vsock_remove_sock(struct vsock_sock *vsk) > } > EXPORT_SYMBOL_GPL(vsock_remove_sock); > > -void vsock_for_each_connected_socket(void (*fn)(struct sock *sk)) > +void vsock_for_each_connected_socket(struct vsock_transport *transport, > + void (*fn)(struct sock *sk)) > { > int i; > > @@ -343,8 +344,12 @@ void vsock_for_each_connected_socket(void (*fn)(struct sock *sk)) > for (i = 0; i < ARRAY_SIZE(vsock_connected_table); i++) { > struct vsock_sock *vsk; > list_for_each_entry(vsk, &vsock_connected_table[i], > - connected_table) > + connected_table) { > + if (vsk->transport != transport) > + continue; > + > fn(sk_vsock(vsk)); > + } > } > > > And all transports that call it. > > Thanks, > Stefano > Thanks for the suggestion, which looks much better. It actually worked well. By the way, the suggested change will alter the kernel-module interface (KMI), which will make it difficult to land the change on older releases where we'd like to keep the KMI stable [1]. Would it be OK if we let the supplied function (fn) be responsible for checking the transport? I think that there, in the future, might be a case where one needs to cycle over all sockets for inspection or so. I admit that this would be prone to error, though. Please let me know what you think. I don't have a strong preference. I will submit a revision as you want. [1] https://source.android.com/devices/architecture/kernel/generic-kernel-image#kmi-stability
