Fine, I will do the corresponding changes and post v5.

Thanks,
Joseph

On 18/3/14 04:19, Tejun Heo wrote:
> Hello, Joseph.
> 
> On Mon, Mar 05, 2018 at 11:03:16PM +0800, Joseph Qi wrote:
>> +static void blkg_pd_offline(struct blkcg_gq *blkg)
>> +{
>> +    int i;
>> +
>> +    lockdep_assert_held(blkg->q->queue_lock);
>> +    lockdep_assert_held(&blkg->blkcg->lock);
>> +
>> +    for (i = 0; i < BLKCG_MAX_POLS; i++) {
>> +            struct blkcg_policy *pol = blkcg_policy[i];
>> +
>> +            if (blkg->pd[i] && !blkg->pd_offline[i] && pol->pd_offline_fn) {
>> +                    pol->pd_offline_fn(blkg->pd[i]);
>> +                    blkg->pd_offline[i] = true;
> 
> Can we move this flag into blkg_policy_data?
> 
>> +    while (!hlist_empty(&blkcg->blkg_list)) {
>> +            struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first,
>> +                                                struct blkcg_gq,
>> +                                                blkcg_node);
>> +            struct request_queue *q = blkg->q;
>> +
>> +            if (spin_trylock(q->queue_lock)) {
>> +                    blkg_destroy(blkg);
>> +                    spin_unlock(q->queue_lock);
>> +            } else {
>> +                    spin_unlock_irq(&blkcg->lock);
>> +                    cpu_relax();
>> +                    spin_lock_irq(&blkcg->lock);
>> +            }
> 
> Can we factor out the above loop?  It's something subtle and painful
> and I think it'd be better to have it separated out and documented.
> 
> Other than that, looks great.
> 
> Thanks.
> 

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