[PATCH] scsi: remove show_use_blk_mq()

[PATCH] scsi: remove show_use_blk_mq()

[Jason Yan]

This code is useless now so remove it.

Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
---
 drivers/scsi/scsi_sysfs.c | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 163dbcb741c1..6480e27982ab 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -386,15 +386,7 @@ show_host_busy(struct device *dev, struct device_attribute *attr, char *buf)
 }
 static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
 
-static ssize_t
-show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
-{
-	return sprintf(buf, "1\n");
-}
-static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);
-
 static struct attribute *scsi_sysfs_shost_attrs[] = {
-	&dev_attr_use_blk_mq.attr,
 	&dev_attr_unique_id.attr,
 	&dev_attr_host_busy.attr,
 	&dev_attr_cmd_per_lun.attr,
-- 
2.17.2

Re: [PATCH] scsi: remove show_use_blk_mq()

[John Garry]

On 01/04/2020 14:40, Jason Yan wrote:
> This code is useless now so remove it.
> 

note: I did not delete this in "scsi: core: Delete scsi_use_blk_mq", to 
avoid risk of breaking some user still using this

thanks,
John

> Cc: Ewan D. Milne <emilne@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>,
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: John Garry <john.garry@huawei.com>
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> ---
>   drivers/scsi/scsi_sysfs.c | 8 --------
>   1 file changed, 8 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 163dbcb741c1..6480e27982ab 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -386,15 +386,7 @@ show_host_busy(struct device *dev, struct device_attribute *attr, char *buf)
>   }
>   static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
>   
> -static ssize_t
> -show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "1\n");
> -}
> -static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);
> -
>   static struct attribute *scsi_sysfs_shost_attrs[] = {
> -	&dev_attr_use_blk_mq.attr,
>   	&dev_attr_unique_id.attr,
>   	&dev_attr_host_busy.attr,
>   	&dev_attr_cmd_per_lun.attr,
> 

Re: [PATCH] scsi: remove show_use_blk_mq()

[Steffen Maier]

On 4/1/20 3:40 PM, Jason Yan wrote:
> This code is useless now so remove it.
> 
> Cc: Ewan D. Milne <emilne@redhat.com>
> Cc: Christoph Hellwig <hch@lst.de>,
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: Ming Lei <ming.lei@redhat.com>
> Cc: John Garry <john.garry@huawei.com>
> Signed-off-by: Jason Yan <yanaijie@huawei.com>
> ---
>   drivers/scsi/scsi_sysfs.c | 8 --------
>   1 file changed, 8 deletions(-)
> 
> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
> index 163dbcb741c1..6480e27982ab 100644
> --- a/drivers/scsi/scsi_sysfs.c
> +++ b/drivers/scsi/scsi_sysfs.c
> @@ -386,15 +386,7 @@ show_host_busy(struct device *dev, struct device_attribute *attr, char *buf)
>   }
>   static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
> 
> -static ssize_t
> -show_use_blk_mq(struct device *dev, struct device_attribute *attr, char *buf)
> -{
> -	return sprintf(buf, "1\n");
> -}
> -static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);
> -
>   static struct attribute *scsi_sysfs_shost_attrs[] = {
> -	&dev_attr_use_blk_mq.attr,

Looks like the removal of a sysfs attribute.
Wouldn't this break user space ABI?
I checked Documentation/ABI/ but could not find this attribute having been 
obsolete (but it does not seem testing or stable either).

[linux/Documentation/ABI](0)$ git grep use_blk_mq .
testing/sysfs-block-dm:41:What:         /sys/block/dm-<num>/dm/use_blk_mq

>   	&dev_attr_unique_id.attr,
>   	&dev_attr_host_busy.attr,
>   	&dev_attr_cmd_per_lun.attr,
> 


-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

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Re: [PATCH] scsi: remove show_use_blk_mq()

[Jason Yan]

在 2020/4/1 21:51, John Garry 写道:
> On 01/04/2020 14:40, Jason Yan wrote:
>> This code is useless now so remove it.
>>
> 
> note: I did not delete this in "scsi: core: Delete scsi_use_blk_mq", to 
> avoid risk of breaking some user still using this
> 

Maybe. But removing a module param may break the user space too.
Actually when the legacy path of single queue is removed, plenty of sys
attributes have been removed. And this one needs to go sooner or later.

> thanks,
> John
> 
>> Cc: Ewan D. Milne <emilne@redhat.com>
>> Cc: Christoph Hellwig <hch@lst.de>,
>> Cc: Hannes Reinecke <hare@suse.de>
>> Cc: Bart Van Assche <bvanassche@acm.org>
>> Cc: Ming Lei <ming.lei@redhat.com>
>> Cc: John Garry <john.garry@huawei.com>
>> Signed-off-by: Jason Yan <yanaijie@huawei.com>
>> ---
>>   drivers/scsi/scsi_sysfs.c | 8 --------
>>   1 file changed, 8 deletions(-)
>>
>> diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
>> index 163dbcb741c1..6480e27982ab 100644
>> --- a/drivers/scsi/scsi_sysfs.c
>> +++ b/drivers/scsi/scsi_sysfs.c
>> @@ -386,15 +386,7 @@ show_host_busy(struct device *dev, struct 
>> device_attribute *attr, char *buf)
>>   }
>>   static DEVICE_ATTR(host_busy, S_IRUGO, show_host_busy, NULL);
>> -static ssize_t
>> -show_use_blk_mq(struct device *dev, struct device_attribute *attr, 
>> char *buf)
>> -{
>> -    return sprintf(buf, "1\n");
>> -}
>> -static DEVICE_ATTR(use_blk_mq, S_IRUGO, show_use_blk_mq, NULL);
>> -
>>   static struct attribute *scsi_sysfs_shost_attrs[] = {
>> -    &dev_attr_use_blk_mq.attr,
>>       &dev_attr_unique_id.attr,
>>       &dev_attr_host_busy.attr,
>>       &dev_attr_cmd_per_lun.attr,
>>
> 
> 
> .

Re: [PATCH] scsi: remove show_use_blk_mq()

[Martin K. Petersen]

Jason,

> Maybe. But removing a module param may break the user space too.

It won't break loading the module.

The intent is to leave the sysfs parameter in place for a while to make
sure nobody depends on it.

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH] scsi: remove show_use_blk_mq()

[Jason Yan]

在 2020/4/2 10:06, Martin K. Petersen 写道:
> 
> Jason,
> 
>> Maybe. But removing a module param may break the user space too.
> 
> It won't break loading the module.
> 
> The intent is to leave the sysfs parameter in place for a while to make
> sure nobody depends on it.
> 

OK, thanks.