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

[Amery Hung]

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)])

> >                               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.

Thanks,
Amery

> Thanks,
> Stefano
>
>
> >+}
> >+
> > static int __vsock_bind_dgram(struct vsock_sock *vsk,
> >                             struct sockaddr_vm *addr)
> > {
> >--
> >2.20.1
> >
>