Re: [PATCH 3/4] io-wq: allow lookup of existing io_wq with given id

[Jens Axboe <axboe@kernel.dk>]

On 1/24/20 2:54 AM, Stefan Metzmacher wrote:
>> +/*
>> + * Find and return io_wq with given id and grab a reference to it.
>> + */
>> +struct io_wq *io_wq_create_id(unsigned bounded, struct io_wq_data *data,
>> +			      unsigned int id)
>> +{
>> +	struct io_wq *wq, *ret = NULL;
>> +
>> +	mutex_lock(&wq_lock);
>> +	list_for_each_entry(wq, &wq_list, wq_list) {
>> +		if (id != wq->id)
>> +			continue;
>> +		if (data->creds != wq->creds || data->user != wq->user)
>> +			continue;
>> +		if (data->get_work != wq->get_work ||
>> +		    data->put_work != wq->put_work)
>> +			continue;
>> +		if (!refcount_inc_not_zero(&wq->use_refs))
>> +			continue;
>> +		ret = wq;
>> +		break;
>> +	}
>> +	mutex_unlock(&wq_lock);
> 
> Isn't there a more efficient ida_find function in order to avoid
> the loop, which won't really scale in the long run.

Yeah that would be a lot better - I initially just used a sequence
for this, but since I'm now using ida, might as well use it for
lookup as well. I'll make the change.

-- 
Jens Axboe