linux-kernel - Re: [PATCH 1/2] scsi: core: Fix sbitmap depth in scsi_realloc_sdev_budget

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Date:   Tue, 15 Mar 2022 15:11:09 +0000
From:   John Garry <john.garry@...wei.com>
To:     Bart Van Assche <bvanassche@....org>,
        <damien.lemoal@...nsource.wdc.com>, <jejb@...ux.ibm.com>,
        <martin.petersen@...cle.com>, <ming.lei@...hat.com>, <hch@....de>,
        <hare@...e.de>
CC:     <linux-ide@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-scsi@...r.kernel.org>, <martin.wilck@...e.com>
Subject: Re: [PATCH 1/2] scsi: core: Fix sbitmap depth in
 scsi_realloc_sdev_budget_map()

On 15/03/2022 14:33, Bart Van Assche wrote:
>> sbitmap sb_backup;
>> +    depth = min_t(unsigned int, depth, 
>> scsi_device_max_queue_depth(sdev));
>> +
>>       /*
>>        * realloc if new shift is calculated, which is caused by setting
>>        * up one new default queue depth after calling ->slave_configure
>> @@ -245,6 +247,9 @@ static int scsi_realloc_sdev_budget_map(struct 
>> scsi_device *sdev,
>>                   scsi_device_max_queue_depth(sdev),
>>                   new_shift, GFP_KERNEL,
>>                   sdev->request_queue->node, false, true);
>> +    if (!ret)
>> +        sbitmap_resize(&sdev->budget_map, depth);
> 
> Hmm ... why to call both sbitmap_init_node() and sbitmap_resize() 
> instead of combining both calls into a single call with the proper depth?

Hi Bart,

Is the user wants to change the queue depth later via sysfs we do not 
reallocate the sbitmap then. So we need to ensure that the size we 
reallocate here will satisfy the scsi device max depth. I'm referencing 
scsi_change_queue_depth() for this.

Thanks,
John