On 2022/2/17 4:48 下午, Christoph Hellwig wrote:
>> {
>> struct request_queue *q = rqos->q;
>> - const char *dir_name = rq_qos_id_to_name(rqos->id);
>> + const char *dir_name;
>> +
>> + dir_name = rqos->ops->name ? rqos->ops->name : rq_qos_id_to_name(rqos->id);
>
> Overly long line here. And it would be much more readable if you used
> a good old if/else.
>
>> +static DEFINE_IDA(rq_qos_ida);
>> +static int nr_rqos_blkcg_pols;
>> +static DEFINE_MUTEX(rq_qos_mutex);
>> +static LIST_HEAD(rq_qos_list);
>
> Please use an allocating xarray instead of an IDA plus list.
>
>> + /*
>> + * queue must have been unregistered here, it is safe to iterate
>> + * the list w/o lock
>> + */
>
> Please capitalize multi-line comments.
>
>> + * After the pluggable blk-qos, rqos's life cycle become complicated,
>> + * as we may modify the rqos list there. Except for the places where
>> + * queue is not registered, there are following places may access rqos
>> + * list concurrently:
>
> Code comments are not the place to explain history. PLease explain the
> current situation.
>
>> +struct rq_qos *rq_qos_get(struct request_queue *q, int id)
>> +{
>> + struct rq_qos *rqos;
>> +
>> + spin_lock_irq(&q->queue_lock);
>
> Please don't use the grab all queue_lock for new code. It badly needs
> to be split and documented, and new code is the best place to start
> that.
>
> Also with all the new code please add a new config option that is
> selected by all rq-pos implementations so that blk-rq-qos.c only gets
> built when actually needed.
>
>> +static inline struct rq_qos *rq_qos_by_id(struct request_queue *q, int id)
>> +{
>> + struct rq_qos *rqos;
>> +
>> + WARN_ON(!mutex_is_locked(&q->sysfs_lock) && !spin_is_locked(&q->queue_lock));
>
> Another overly long line. And in doubt split this into two helpers
> so that you cna use lockdep_assert_held instead of doing the incorrect
> asserts.
Thanks so much for your kindly comment. I'd change the code in next version.
Regards
Jianchao
