[PATCH] nvme: add 'kato' sysfs attribute

[PATCH] nvme: add 'kato' sysfs attribute

[Hannes Reinecke]

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@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
 };
 
-- 
2.26.2


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Re: [PATCH] nvme: add 'kato' sysfs attribute

[Daniel Wagner]

On Fri, Feb 26, 2021 at 08:52:51AM +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@suse.de>

Reviewed-by: Daniel Wagner <dwagner@suse.de>

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Re: [PATCH] nvme: add 'kato' sysfs attribute

[George, Martin]

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@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.

-Martin
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Re: [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@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@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer

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