From: "yukuai (C)" <yukuai3@huawei.com>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
<cgroups@vger.kernel.org>,
linux-block <linux-block@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>, <yi.zhang@huawei.com>
Subject: Re: [PATCH RFC 8/9] block, bfq: move forward __bfq_weights_tree_remove()
Date: Sat, 11 Dec 2021 10:18:53 +0800 [thread overview]
Message-ID: <93f26416-19d9-43f6-01ad-652c1b763d09@huawei.com> (raw)
In-Reply-To: <FA78962A-DC03-4A1F-9B79-D085A4908E5E@linaro.org>
在 2021/12/10 18:00, Paolo Valente 写道:
>
>
>> Il giorno 27 nov 2021, alle ore 11:11, Yu Kuai <yukuai3@huawei.com> ha scritto:
>>
>> Prepare to decrease 'num_groups_with_pending_reqs' earlier.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>> block/bfq-iosched.c | 13 +++++--------
>> 1 file changed, 5 insertions(+), 8 deletions(-)
>>
>> diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
>> index e3c31db4bffb..4239b3996e23 100644
>> --- a/block/bfq-iosched.c
>> +++ b/block/bfq-iosched.c
>> @@ -882,6 +882,10 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,
>> {
>> struct bfq_entity *entity = bfqq->entity.parent;
>>
>> + bfqq->ref++;
>> + __bfq_weights_tree_remove(bfqd, bfqq,
>> + &bfqd->queue_weights_tree);
>> +
>> for_each_entity(entity) {
>> struct bfq_sched_data *sd = entity->my_sched_data;
>>
>> @@ -916,14 +920,7 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd,
>> }
>> }
>>
>> - /*
>> - * Next function is invoked last, because it causes bfqq to be
>> - * freed if the following holds: bfqq is not in service and
>> - * has no dispatched request. DO NOT use bfqq after the next
>> - * function invocation.
>> - */
>> - __bfq_weights_tree_remove(bfqd, bfqq,
>> - &bfqd->queue_weights_tree);
>> + bfq_put_queue(bfqq);
>> }
>>
>
> why it is not dangerous any longer to invoke __bfq_weights_tree_remove earlier, and the comment can be removed?
Hi, Paolo
Here I grab an additional ref to the bfqq, thus the bfqq is ensured not
to be free before bfq_put_queue() at the end of the function.
Maybe some comments is more appropriate.
Thanks,
Kuai
>
> Paolo
>
>> /*
>> --
>> 2.31.1
>>
>
> .
>
next prev parent reply other threads:[~2021-12-11 2:19 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-27 10:11 [PATCH RFC 0/9] support concurrent sync io for bfq on a specail occasion Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 1/9] block, bfq: add new apis to iterate bfq entities Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 2/9] block, bfq: apply news apis where root group is not expected Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 3/9] block, bfq: handle the case when for_each_entity() access root group Yu Kuai
2021-12-10 10:06 ` Paolo Valente
2021-11-27 10:11 ` [PATCH RFC 4/9] block, bfq: count root group into 'num_groups_with_pending_reqs' Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 5/9] block, bfq: do not idle if only one cgroup is activated Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 6/9] block, bfq: only count group that the bfq_queue belongs to Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 7/9] block, bfq: record how many queues have pending requests in bfq_group Yu Kuai
2021-11-27 10:11 ` [PATCH RFC 8/9] block, bfq: move forward __bfq_weights_tree_remove() Yu Kuai
2021-12-10 10:00 ` Paolo Valente
2021-12-11 2:18 ` yukuai (C) [this message]
2021-11-27 10:11 ` [PATCH RFC 9/9] block, bfq: decrease 'num_groups_with_pending_reqs' earlier Yu Kuai
2021-12-10 10:21 ` Paolo Valente
2021-12-11 2:10 ` yukuai (C)
2021-12-16 16:34 ` Paolo Valente
2021-12-17 2:53 ` yukuai (C)
2021-12-10 8:20 ` [PATCH RFC 0/9] support concurrent sync io for bfq on a specail occasion yukuai (C)
2021-12-10 9:20 ` Paolo Valente
2021-12-10 9:50 ` yukuai (C)
2021-12-10 10:23 ` Paolo Valente
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