On Wed, 2016-09-28 at 12:52 +0200, Paolo Abeni wrote:
> +static void udp_rmem_release(struct sock *sk, int partial)
> +{
> + struct udp_sock *up = udp_sk(sk);
> + int fwd, amt;
> +
> + if (partial && !udp_under_memory_pressure(sk))
> + return;
> +
> + /* we can have concurrent release; if we catch any conflict
> + * we let only one of them do the work
> + */
> + if (atomic_dec_if_positive(&up->can_reclaim) < 0)
> + return;
> +
> + fwd = __udp_forward(up, atomic_read(&sk->sk_rmem_alloc));
> + if (fwd < SK_MEM_QUANTUM + partial) {
> + atomic_inc(&up->can_reclaim);
> + return;
> + }
> +
> + amt = (fwd - partial) & ~(SK_MEM_QUANTUM - 1);
> + atomic_sub(amt, &up->mem_allocated);
> + atomic_inc(&up->can_reclaim);
> +
> + __sk_mem_reduce_allocated(sk, amt >> SK_MEM_QUANTUM_SHIFT);
> + sk->sk_forward_alloc = fwd - amt;
> +}
This is racy... all these atomics make me nervous...
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