On 11/8/18 8:54 AM, Laurence Oberman wrote:
> On Thu, 2018-11-08 at 08:42 -0700, Jens Axboe wrote:
>> +static bool blk_mq_check_busy(struct blk_mq_hw_ctx *hctx, struct
>> request *rq,
>> + void *priv, bool reserved)
>> +{
>> + bool *busy = (bool *) priv;
>> +
>> + /*
>> + * If we find a request, we know the queue is busy. Return
>> false
>> + * to stop the iteration.
>> + */
>> + *busy = true;
>> + return false;
>> +}
>> +
>
> Hi Jens,
>
> Trying to understand the logic, likely just my lack of knowledge
> You return false after setting true because you say we know the queue
> is busy.
> How do we know we found a request here
> I dont see you check the result of
> bool *busy = (bool *) priv;
> Is the assumption here because this was called we already knew we had a
> request
Yes, that's absolutely right - if we get into the helper, we know we
already have a request. Hence we know the queue is busy. Actually
thinking about it, for shared tags, we need to check if the request
is for the given queue. Will send a v2...
--
Jens Axboe
