Re: [RFC PATCH net-next v6 04/14] af_vsock: generalize bind table functions

[Stefano Garzarella]

On Sun, Jul 28, 2024 at 11:52:54AM GMT, Amery Hung wrote:
> On Tue, Jul 23, 2024 at 7:40 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
> > On Wed, Jul 10, 2024 at 09:25:45PM GMT, Amery Hung wrote:
> > >From: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
> > >
> > >This commit makes the bind table management functions in vsock usable
> > >for different bind tables. Future work will introduce a new table for
> > >datagrams to avoid address collisions, and these functions will be used
> > >there.
> > >
> > >Signed-off-by: Bobby Eshleman <bobby.eshleman@xxxxxxxxxxxxx>
> > >---
> > > net/vmw_vsock/af_vsock.c | 34 +++++++++++++++++++++++++++-------
> > > 1 file changed, 27 insertions(+), 7 deletions(-)
> > >
> > >diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> > >index acc15e11700c..d571be9cdbf0 100644
> > >--- a/net/vmw_vsock/af_vsock.c
> > >+++ b/net/vmw_vsock/af_vsock.c
> > >@@ -232,11 +232,12 @@ static void __vsock_remove_connected(struct vsock_sock *vsk)
> > >       sock_put(&vsk->sk);
> > > }
> > >
> > >-static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > >+static struct sock *vsock_find_bound_socket_common(struct sockaddr_vm *addr,
> > >+                                                 struct list_head *bind_table)
> > > {
> > >       struct vsock_sock *vsk;
> > >
> > >-      list_for_each_entry(vsk, vsock_bound_sockets(addr), bound_table) {
> > >+      list_for_each_entry(vsk, bind_table, bound_table) {
> > >               if (vsock_addr_equals_addr(addr, &vsk->local_addr))
> > >                       return sk_vsock(vsk);
> > >
> > >@@ -249,6 +250,11 @@ static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > >       return NULL;
> > > }
> > >
> > >+static struct sock *__vsock_find_bound_socket(struct sockaddr_vm *addr)
> > >+{
> > >+      return vsock_find_bound_socket_common(addr, vsock_bound_sockets(addr));
> > >+}
> > >+
> > > static struct sock *__vsock_find_connected_socket(struct sockaddr_vm *src,
> > >                                                 struct sockaddr_vm *dst)
> > > {
> > >@@ -671,12 +677,18 @@ static void vsock_pending_work(struct work_struct *work)
> > >
> > > /**** SOCKET OPERATIONS ****/
> > >
> > >-static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > >-                                  struct sockaddr_vm *addr)
> > >+static int vsock_bind_common(struct vsock_sock *vsk,
> > >+                           struct sockaddr_vm *addr,
> > >+                           struct list_head *bind_table,
> > >+                           size_t table_size)
> > > {
> > >       static u32 port;
> > >       struct sockaddr_vm new_addr;
> > >
> > >+      if (WARN_ONCE(table_size < VSOCK_HASH_SIZE,
> > >+                    "table size too small, may cause overflow"))
> > >+              return -EINVAL;
> > >+
> >
> > I'd add this in another commit.
> >
> > >       if (!port)
> > >               port = get_random_u32_above(LAST_RESERVED_PORT);
> > >
> > >@@ -692,7 +704,8 @@ static int __vsock_bind_connectible(struct
> > >vsock_sock *vsk,
> > >
> > >                       new_addr.svm_port = port++;
> > >
> > >-                      if (!__vsock_find_bound_socket(&new_addr)) {
> > >+                      if (!vsock_find_bound_socket_common(&new_addr,
> > >+                                                          &bind_table[VSOCK_HASH(addr)])) {
> >
> > Can we add a macro for `&bind_table[VSOCK_HASH(addr)])` ?
>
> Definitely. I will add the following macro:
>
> #define vsock_bound_sockets_in_table(bind_table, addr) \
>        (&bind_table[VSOCK_HASH(addr)])

yeah.

> > >                               found = true;
> > >                               break;
> > >                       }
> > >@@ -709,7 +722,8 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > >                       return -EACCES;
> > >               }
> > >
> > >-              if (__vsock_find_bound_socket(&new_addr))
> > >+              if (vsock_find_bound_socket_common(&new_addr,
> > >+                                                 &bind_table[VSOCK_HASH(addr)]))
> > >                       return -EADDRINUSE;
> > >       }
> > >
> > >@@ -721,11 +735,17 @@ static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > >        * by AF_UNIX.
> > >        */
> > >       __vsock_remove_bound(vsk);
> > >-      __vsock_insert_bound(vsock_bound_sockets(&vsk->local_addr), vsk);
> > >+      __vsock_insert_bound(&bind_table[VSOCK_HASH(&vsk->local_addr)], vsk);
> > >
> > >       return 0;
> > > }
> > >
> > >+static int __vsock_bind_connectible(struct vsock_sock *vsk,
> > >+                                  struct sockaddr_vm *addr)
> > >+{
> > >+      return vsock_bind_common(vsk, addr, vsock_bind_table, VSOCK_HASH_SIZE + 1);
> >
> > What about using ARRAY_SIZE(x) ?
> >
> > BTW we are using that size just to check it, but all the arrays we use
> > are statically allocated, so what about a compile time check like
> > BUILD_BUG_ON()?
>
> I will remove the table_size check you mentioned earlier and the
> argument here as the arrays are allocated statically like you
> mentioned.
>
> If you think this check may be a good addition, I can add a
> BUILD_BUG_ON() in the new vsock_bound_sockets_in_table() macro.

If you want to add it, we need to do it in a separate commit. But since 
we already have so many changes and both arrays are statically allocated 
in the same file, IMHO we can avoid the check.

Stefano