[PATCH] nvme: add 'kato' sysfs attribute

[Hannes Reinecke]

On 3/1/21 4:39 PM, George, Martin wrote:
> On Fri, 2021-02-26 at 08:52 +0100, Hannes Reinecke wrote:
>> Add a 'kato' controller sysfs attribute to display the current
>> keep-alive timeout value (if any). This allows userspace to identify
>> persistent discovery controllers, as these will have a non-zero
>> KATO value.
>>
>> Signed-off-by: Hannes Reinecke <hare at suse.de>
>> ---
>>   drivers/nvme/host/core.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
>> index 1d5fc8a6fd37..9ad23472ac15 100644
>> --- a/drivers/nvme/host/core.c
>> +++ b/drivers/nvme/host/core.c
>> @@ -3547,6 +3547,7 @@ nvme_show_int_function(cntlid);
>>   nvme_show_int_function(numa_node);
>>   nvme_show_int_function(queue_count);
>>   nvme_show_int_function(sqsize);
>> +nvme_show_int_function(kato);
>>
>>   static ssize_t nvme_sysfs_delete(struct device *dev,
>>                                  struct device_attribute *attr, const
>> char *buf,
>> @@ -3749,6 +3750,7 @@ static struct attribute *nvme_dev_attrs[] = {
>>          &dev_attr_ctrl_loss_tmo.attr,
>>          &dev_attr_fast_io_fail_tmo.attr,
>>          &dev_attr_reconnect_delay.attr,
>> +       &dev_attr_kato.attr,
>>          NULL
>>   };
>>
> 
> This is helpful indeed. But looks like the actual kato value sent down
> the wire is ctrl->kato + NVME_KATO_GRACE. Wondering if that may end up
> confusing the end user.
> 
For that I had another patch sent, 'nvme: sanitize KATO setting'.
Might be an idea to roll this one into that set to make it clear.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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