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Message-ID: <93f26416-19d9-43f6-01ad-652c1b763d09@huawei.com>
Date: Sat, 11 Dec 2021 10:18:53 +0800
From: "yukuai (C)" <yukuai3@...wei.com>
To: Paolo Valente <paolo.valente@...aro.org>
CC: Tejun Heo <tj@...nel.org>, Jens Axboe <axboe@...nel.dk>,
<cgroups@...r.kernel.org>,
linux-block <linux-block@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>, <yi.zhang@...wei.com>
Subject: Re: [PATCH RFC 8/9] block, bfq: move forward
__bfq_weights_tree_remove()
在 2021/12/10 18:00, Paolo Valente 写道:
>
>
>> Il giorno 27 nov 2021, alle ore 11:11, Yu Kuai <yukuai3@...wei.com> ha scritto:
>>
>> Prepare to decrease 'num_groups_with_pending_reqs' earlier.
>>
>> Signed-off-by: Yu Kuai <yukuai3@...wei.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
>>
>
> .
>
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