[PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[Yajun Deng]

phys_port_id_show, phys_port_name_show and phys_switch_id_show would
return -EOPNOTSUPP if the netdev didn't implement the corresponding
method.

There is no point in creating these files if they are unsupported.

Put these attributes in netdev_phys_group and implement the is_visible
method. make phys_(port_id, port_name, switch_id) invisible if the netdev
dosen't implement the corresponding method.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v2: Remove worthless comments
v1: https://lore.kernel.org/all/20250515130205.3274-1-yajun.deng@linux.dev/
---
 include/linux/netdevice.h |  2 +-
 net/core/net-sysfs.c      | 68 +++++++++++++++++++++++----------------
 2 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 32a1e41636a9..efbcc4836498 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2384,7 +2384,7 @@ struct net_device {
 	struct dm_hw_stat_delta __rcu *dm_private;
 #endif
 	struct device		dev;
-	const struct attribute_group *sysfs_groups[4];
+	const struct attribute_group *sysfs_groups[5];
 	const struct attribute_group *sysfs_rx_queue_group;
 
 	const struct rtnl_link_ops *rtnl_link_ops;
diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 1ace0cd01adc..f626dcd66d03 100644
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -641,12 +641,6 @@ static ssize_t phys_port_id_show(struct device *dev,
 	struct netdev_phys_item_id ppid;
 	ssize_t ret;
 
-	/* The check is also done in dev_get_phys_port_id; this helps returning
-	 * early without hitting the locking section below.
-	 */
-	if (!netdev->netdev_ops->ndo_get_phys_port_id)
-		return -EOPNOTSUPP;
-
 	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
 	if (ret)
 		return ret;
@@ -659,7 +653,8 @@ static ssize_t phys_port_id_show(struct device *dev,
 
 	return ret;
 }
-static DEVICE_ATTR_RO(phys_port_id);
+static struct device_attribute dev_attr_phys_port_id =
+	__ATTR(phys_port_id, 0444, phys_port_id_show, NULL);
 
 static ssize_t phys_port_name_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
@@ -668,13 +663,6 @@ static ssize_t phys_port_name_show(struct device *dev,
 	char name[IFNAMSIZ];
 	ssize_t ret;
 
-	/* The checks are also done in dev_get_phys_port_name; this helps
-	 * returning early without hitting the locking section below.
-	 */
-	if (!netdev->netdev_ops->ndo_get_phys_port_name &&
-	    !netdev->devlink_port)
-		return -EOPNOTSUPP;
-
 	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
 	if (ret)
 		return ret;
@@ -687,7 +675,8 @@ static ssize_t phys_port_name_show(struct device *dev,
 
 	return ret;
 }
-static DEVICE_ATTR_RO(phys_port_name);
+static struct device_attribute dev_attr_phys_port_name =
+	__ATTR(phys_port_name, 0444, phys_port_name_show, NULL);
 
 static ssize_t phys_switch_id_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
@@ -696,14 +685,6 @@ static ssize_t phys_switch_id_show(struct device *dev,
 	struct netdev_phys_item_id ppid = { };
 	ssize_t ret;
 
-	/* The checks are also done in dev_get_phys_port_name; this helps
-	 * returning early without hitting the locking section below. This works
-	 * because recurse is false when calling dev_get_port_parent_id.
-	 */
-	if (!netdev->netdev_ops->ndo_get_port_parent_id &&
-	    !netdev->devlink_port)
-		return -EOPNOTSUPP;
-
 	ret = sysfs_rtnl_lock(&dev->kobj, &attr->attr, netdev);
 	if (ret)
 		return ret;
@@ -716,7 +697,42 @@ static ssize_t phys_switch_id_show(struct device *dev,
 
 	return ret;
 }
-static DEVICE_ATTR_RO(phys_switch_id);
+static struct device_attribute dev_attr_phys_switch_id =
+	__ATTR(phys_switch_id, 0444, phys_switch_id_show, NULL);
+
+static struct attribute *netdev_phys_attrs[] __ro_after_init = {
+	&dev_attr_phys_port_id.attr,
+	&dev_attr_phys_port_name.attr,
+	&dev_attr_phys_switch_id.attr,
+	NULL,
+};
+
+static umode_t netdev_phys_is_visible(struct kobject *kobj,
+				      struct attribute *attr, int index)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct net_device *netdev = to_net_dev(dev);
+
+	if (attr == &dev_attr_phys_port_id.attr) {
+		if (!netdev->netdev_ops->ndo_get_phys_port_id)
+			return 0;
+	} else if (attr == &dev_attr_phys_port_name.attr) {
+		if (!netdev->netdev_ops->ndo_get_phys_port_name &&
+		    !netdev->devlink_port)
+			return 0;
+	} else if (attr == &dev_attr_phys_switch_id.attr) {
+		if (!netdev->netdev_ops->ndo_get_port_parent_id &&
+		    !netdev->devlink_port)
+			return 0;
+	}
+
+	return attr->mode;
+}
+
+static const struct attribute_group netdev_phys_group = {
+	.attrs = netdev_phys_attrs,
+	.is_visible = netdev_phys_is_visible,
+};
 
 static ssize_t threaded_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
@@ -783,9 +799,6 @@ static struct attribute *net_class_attrs[] __ro_after_init = {
 	&dev_attr_tx_queue_len.attr,
 	&dev_attr_gro_flush_timeout.attr,
 	&dev_attr_napi_defer_hard_irqs.attr,
-	&dev_attr_phys_port_id.attr,
-	&dev_attr_phys_port_name.attr,
-	&dev_attr_phys_switch_id.attr,
 	&dev_attr_proto_down.attr,
 	&dev_attr_carrier_up_count.attr,
 	&dev_attr_carrier_down_count.attr,
@@ -2328,6 +2341,7 @@ int netdev_register_kobject(struct net_device *ndev)
 		groups++;
 
 	*groups++ = &netstat_group;
+	*groups++ = &netdev_phys_group;
 
 	if (wireless_group_needed(ndev))
 		*groups++ = &wireless_group;
-- 
2.25.1

Re: [PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[Simon Horman]

On Wed, May 21, 2025 at 10:08:24PM +0800, Yajun Deng wrote:
> phys_port_id_show, phys_port_name_show and phys_switch_id_show would
> return -EOPNOTSUPP if the netdev didn't implement the corresponding
> method.
> 
> There is no point in creating these files if they are unsupported.
> 
> Put these attributes in netdev_phys_group and implement the is_visible
> method. make phys_(port_id, port_name, switch_id) invisible if the netdev
> dosen't implement the corresponding method.
> 
> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
> ---
> v2: Remove worthless comments
> v1: https://lore.kernel.org/all/20250515130205.3274-1-yajun.deng@linux.dev/

Reviewed-by: Simon Horman <horms@kernel.org>

FWIIW, I had the same thought that Jakub related in his review of v1.

 "I'm slightly worried some user space depends on the files existing,
  but maybe ENOENT vs EOPNOTSUPP doesn't make a big difference.|

...

Re: [PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[Paolo Abeni]

On 5/21/25 4:08 PM, Yajun Deng wrote:
> phys_port_id_show, phys_port_name_show and phys_switch_id_show would
> return -EOPNOTSUPP if the netdev didn't implement the corresponding
> method.
> 
> There is no point in creating these files if they are unsupported.
> 
> Put these attributes in netdev_phys_group and implement the is_visible
> method. make phys_(port_id, port_name, switch_id) invisible if the netdev
> dosen't implement the corresponding method.
> 
> Signed-off-by: Yajun Deng <yajun.deng@linux.dev>

I fear that some orchestration infra depends on the files existence -
i.e. scripts don't tolerate the files absence, deal only with I/O errors
after open.

It feel a bit too dangerous to merge a change that could break
user-space this late. Let's defer it to the beginning of the next cycle.

Paolo

Re: [PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[Yajun Deng]

May 27, 2025 at 2:08 PM, "Paolo Abeni" <pabeni@redhat.com> wrote:



> 
> On 5/21/25 4:08 PM, Yajun Deng wrote:
> 
> > 
> > phys_port_id_show, phys_port_name_show and phys_switch_id_show would
> > 
> >  return -EOPNOTSUPP if the netdev didn't implement the corresponding
> > 
> >  method.
> > 
> >  
> > 
> >  There is no point in creating these files if they are unsupported.
> > 
> >  
> > 
> >  Put these attributes in netdev_phys_group and implement the is_visible
> > 
> >  method. make phys_(port_id, port_name, switch_id) invisible if the netdev
> > 
> >  dosen't implement the corresponding method.
> > 
> >  
> > 
> >  Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
> > 
> 
> I fear that some orchestration infra depends on the files existence -
> 
> i.e. scripts don't tolerate the files absence, deal only with I/O errors
> 
> after open.
> 
> It feel a bit too dangerous to merge a change that could break
> 
> user-space this late. Let's defer it to the beginning of the next cycle.
> 

Ping.

> Paolo
>

Re: [PATCH net-next v2] net: sysfs: Implement is_visible for phys_(port_id, port_name, switch_id)

[Paolo Abeni]

On 6/12/25 10:51 AM, Yajun Deng wrote:
> May 27, 2025 at 2:08 PM, "Paolo Abeni" <pabeni@redhat.com> wrote:
>> On 5/21/25 4:08 PM, Yajun Deng wrote:
>>> phys_port_id_show, phys_port_name_show and phys_switch_id_show would
>>>
>>>  return -EOPNOTSUPP if the netdev didn't implement the corresponding
>>>
>>>  method.
>>>
>>>  
>>>
>>>  There is no point in creating these files if they are unsupported.
>>>
>>>  
>>>
>>>  Put these attributes in netdev_phys_group and implement the is_visible
>>>
>>>  method. make phys_(port_id, port_name, switch_id) invisible if the netdev
>>>
>>>  dosen't implement the corresponding method.
>>>
>>>  
>>>
>>>  Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
>>>
>>
>> I fear that some orchestration infra depends on the files existence -
>>
>> i.e. scripts don't tolerate the files absence, deal only with I/O errors
>>
>> after open.
>>
>> It feel a bit too dangerous to merge a change that could break
>>
>> user-space this late. Let's defer it to the beginning of the next cycle.
>>
> 
> Ping.

I was likely not clear. The above means you should re-submit the patch now.

/P