On Mon, 2016-11-21 at 14:57 +0100, Florian Westphal wrote:
...
> #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
> +#define XT_PCPU_BLOCK_SIZE 4096
>
> struct compat_delta {
> unsigned int offset; /* offset in kernel */
> @@ -1618,6 +1619,7 @@ EXPORT_SYMBOL_GPL(xt_proto_fini);
> /**
> * xt_percpu_counter_alloc - allocate x_tables rule counter
> *
> + * @state: pointer to xt_percpu allocation state
> * @counter: pointer to counter struct inside the ip(6)/arpt_entry struct
> *
> * On SMP, the packet counter [ ip(6)t_entry->counters.pcnt ] will then
> @@ -1626,20 +1628,33 @@ EXPORT_SYMBOL_GPL(xt_proto_fini);
> * Rule evaluation needs to use xt_get_this_cpu_counter() helper
> * to fetch the real percpu counter.
> *
> + * To speed up allocation and improve data locality, an entire
> + * page is allocated.
* To speed up allocation and improve data locality, a 4KB bloc
* is allocated.
> + *
> + * xt_percpu_counter_alloc_state contains the base address of the
> + * allocated page and the current sub-offset.
> + *
> * returns false on error.
> */
> -bool xt_percpu_counter_alloc(struct xt_counters *counter)
> +bool xt_percpu_counter_alloc(struct xt_percpu_counter_alloc_state *state,
> + struct xt_counters *counter)
> {
> - void __percpu *res;
> + BUILD_BUG_ON(XT_PCPU_BLOCK_SIZE < (sizeof(*counter) * 2));
>
> - if (nr_cpu_ids > 1) {
> - res = __alloc_percpu(sizeof(struct xt_counters),
> - sizeof(struct xt_counters));
> + if (nr_cpu_ids <= 1)
> + return true;
>
> - if (!res)
> + if (state->mem == NULL) {
if (!state->mem) {
> + state->mem = __alloc_percpu(XT_PCPU_BLOCK_SIZE, XT_PCPU_BLOCK_SIZE);
> + if (!state->mem)
(to be consistent with this test )
> return false;
> }
> - counter->pcnt = (__force unsigned long)res;
> + counter->pcnt = (__force unsigned long)(state->mem + state->off);
> + state->off += sizeof(*counter);
> + if (state->off > (XT_PCPU_BLOCK_SIZE - sizeof(*counter))) {
> + state->mem = NULL;
> + state->off = 0;
> + }
--
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