Re: [PATCH bpf-next v5 1/3] devmap/cpumap: Use flush list instead of bitmap

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Daniel Borkmann <daniel@iogearbox.net> writes:

> On 06/23/2019 04:17 AM, Toke Høiland-Jørgensen wrote:
>> From: Toke Høiland-Jørgensen <toke@redhat.com>
>> 
>> The socket map uses a linked list instead of a bitmap to keep track of
>> which entries to flush. Do the same for devmap and cpumap, as this means we
>> don't have to care about the map index when enqueueing things into the
>> map (and so we can cache the map lookup).
>> 
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> [...]
>> +static int bq_flush_to_queue(struct xdp_bulk_queue *bq, bool in_napi_ctx)
>>  {
>> +	struct bpf_cpu_map_entry *rcpu = bq->obj;
>>  	unsigned int processed = 0, drops = 0;
>>  	const int to_cpu = rcpu->cpu;
>>  	struct ptr_ring *q;
>> @@ -621,6 +630,9 @@ static int bq_flush_to_queue(struct bpf_cpu_map_entry *rcpu,
>>  	bq->count = 0;
>>  	spin_unlock(&q->producer_lock);
>>  
>> +	__list_del(bq->flush_node.prev, bq->flush_node.next);
>> +	bq->flush_node.prev = NULL;
>
> Given this and below is a bit non-standard way of using list API, maybe add
> these as inline helpers to include/linux/list.h to make sure anyone changing
> list API semantics doesn't overlook these in future?

Sure, can do.

-Toke