>> +static inline bool nvme_rdma_queue_sig_limit(struct nvme_rdma_queue *queue)
>> +{
>> + int v, old;
>> +
>> + v = atomic_read(&queue->sig_count);
>> + while (1) {
>> + if (v > 1) {
>> + old = atomic_cmpxchg(&queue->sig_count, v, v - 1);
>> + if (old == v)
>> + return false;
>> + } else {
>> + int new_count;
>> +
>> + new_count = nvme_rdma_init_sig_count(queue->queue_size);
>> + old = atomic_cmpxchg(&queue->sig_count, v, new_count);
>> + if (old == v)
>> + return true;
>> + }
>> + v = old;
>> + }
>> +}
>> +
>
> Ugh, no...
>
> How about just do:
>
> if (atomic_inc_return(queue->sig_count) % queue->sig_limit)
> return true;
> return false;
>
> where
> queue->sig_limit = max(queue->queue_size / 2, 1);
I tried to avoid that because this adds a division in the fast path Bart
was unhappy about in v2.
Unfortunately we do not have an atomic with on overflow operation like
the one needed here.
Marta
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