Re: [PATCH] net: convert sk_filter.refcnt from atomic_t to refcount_t

[Daniel Borkmann]

On 03/20/2017 10:37 AM, Elena Reshetova wrote:
[...]

diff --git a/net/core/filter.c b/net/core/filter.c
index ebaeaf2..389cb8d 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -928,7 +928,7 @@ static void sk_filter_release_rcu(struct rcu_head *rcu)
   */
  static void sk_filter_release(struct sk_filter *fp)
  {
-       if (atomic_dec_and_test(&fp->refcnt))
+       if (refcount_dec_and_test(&fp->refcnt))
                call_rcu(&fp->rcu, sk_filter_release_rcu);
  }

@@ -943,20 +943,27 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter 
*fp)
  /* try to charge the socket memory if there is space available
   * return true on success
   */
-bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
+bool __sk_filter_charge(struct sock *sk, struct sk_filter *fp)

And this then becomes: static bool __sk_filter_charge(...)

  {
        u32 filter_size = bpf_prog_size(fp->prog->len);

        /* same check as in sock_kmalloc() */
        if (filter_size <= sysctl_optmem_max &&
            atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) {
-               atomic_inc(&fp->refcnt);
                atomic_add(filter_size, &sk->sk_omem_alloc);
                return true;
        }
        return false;
  }

Since here is just all in slow-path, looks fine to me if the above
is addressed as well in v3:

Acked-by: Daniel Borkmann <dan...@iogearbox.net>

Please make sure you add [PATCH net-next] in your subject in future
so that it's clear which tree this goes to.

Thanks,
Daniel