[PATCH V2 5/5] blk-mq: Replace tags->lock with SRCU for tag iterators - Rockchip UFS regression

[Jens Axboe]

On 10/6/25 12:02 PM, Bart Van Assche wrote:
> On 10/4/25 7:42 AM, Ming Lei wrote:
>>    One possible fix is to check hba->scsi_host_added before calling
>> scsi_host_busy():
>>
>>    dev_err(hba->dev, "%d outstanding reqs, tasks=0x%lx\n",
>>        hba->scsi_host_added ? scsi_host_busy(hba->host) : 0,
>>        hba->outstanding_tasks);
> 
> My preference is to add a check inside scsi_host_busy(), e.g. as follows
> (entirely untested):
> 
> diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
> index cc5d05dc395c..17173239301e 100644
> --- a/drivers/scsi/hosts.c
> +++ b/drivers/scsi/hosts.c
> @@ -611,8 +611,9 @@ int scsi_host_busy(struct Scsi_Host *shost)
>  {
>      int cnt = 0;
> 
> -    blk_mq_tagset_busy_iter(&shost->tag_set,
> -                scsi_host_check_in_flight, &cnt);
> +    if (shost->tag_set.ops)
> +        blk_mq_tagset_busy_iter(&shost->tag_set,
> +                    scsi_host_check_in_flight, &cnt);
>      return cnt;
>  }
>  EXPORT_SYMBOL(scsi_host_busy);

Agree, that's a nicer way to solve it, putting that stuff outside
of actual drivers.

-- 
Jens Axboe