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SubjectRe: [PATCH] blk-iocost: initialize rqos before accessing it
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On 2/26/23 9:55 AM, Tejun Heo wrote:
> Hello, Breno.
>
> On Fri, Feb 24, 2023 at 08:07:14AM -0800, Breno Leitao wrote:
>> diff --git a/block/blk-iocost.c b/block/blk-iocost.c
>> index ff534e9d92dc..6cced8a76e9c 100644
>> --- a/block/blk-iocost.c
>> +++ b/block/blk-iocost.c
>> @@ -2878,11 +2878,6 @@ static int blk_iocost_init(struct gendisk *disk)
>> atomic64_set(&ioc->cur_period, 0);
>> atomic_set(&ioc->hweight_gen, 0);
>>
>> - spin_lock_irq(&ioc->lock);
>> - ioc->autop_idx = AUTOP_INVALID;
>> - ioc_refresh_params(ioc, true);
>> - spin_unlock_irq(&ioc->lock);
>> -
>> /*
>> * rqos must be added before activation to allow ioc_pd_init() to
>> * lookup the ioc from q. This means that the rqos methods may get
>> @@ -2893,6 +2888,11 @@ static int blk_iocost_init(struct gendisk *disk)
>> if (ret)
>> goto err_free_ioc;
>>
>> + spin_lock_irq(&ioc->lock);
>> + ioc->autop_idx = AUTOP_INVALID;
>> + ioc_refresh_params(ioc, true);
>> + spin_unlock_irq(&ioc->lock);
>> +
>
> I'm a bit worried about registering the rqos before ioc_refresh_params() as
> that initializes all the internal parameters and letting IOs flow through
> without initializing them can lead to subtle issues. Can you please instead
> explicitly pass @q into ioc_refresh_params() (and explain why we need it
> passed explicitly in the function comment)?

Sorry missed this, I'll drop it for now.

--
Jens Axboe


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