Messages in this thread | | | Date | Thu, 17 Feb 2022 00:48:43 -0800 | From | Christoph Hellwig <> | Subject | Re: [RFC V4 1/6] blk: prepare to make blk-rq-qos pluggable and modular |
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> { > 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.
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