Re: [PATCH net-next v3 12/15] ibmveth: Expose per-queue buffer pool details via sysfs

On 7/14/26 6:01 AM, Simon Horman wrote:

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ibmveth: Expose per-queue buffer pool details via sysfs

This commit adds a read-only sysfs attribute buffer_pools to the VIO device
to expose per-queue buffer pool details dynamically. It outputs runtime per-queue
buffer pressure metrics like size, active, and available buffers.

quoted

diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index 4e3f49b6346fd..ecc472ee8f71f 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c

@@ -2896,6 +2896,52 @@ static const struct net_device_ops ibmveth_netdev_ops = {

[ ... ]

quoted

+static ssize_t buffer_pools_show(struct device *dev,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct net_device *netdev = dev_get_drvdata(dev);
+	struct ibmveth_adapter *adapter = netdev_priv(netdev);
+	int len = 0;
+	int i, j;
+
+	len += scnprintf(buf + len, PAGE_SIZE - len,
+			 "Queue  Pool  Size  BuffSize  Active  Available\n");
+	len += scnprintf(buf + len, PAGE_SIZE - len,
+			 "-----  ----  ----  --------  ------  ---------\n");

[Severity: Medium]
Does this buffer_pools_show() implementation violate the sysfs "one value
per file" design rule?

The attribute appears to dump a complex, multi-line ASCII table with headers
and columns rather than exposing a single value per sysfs file.

*

  Agreed this is more of a diagnostic dump than a sysfs one-value

  attribute. In v4 I’ll move it to debugfs ?

*

[ ... ]

quoted

@@ -3056,6 +3102,14 @@ static int ibmveth_probe(struct vio_dev *dev, const struct vio_device_id *id)
  
  	netdev_dbg(netdev, "registered\n");
  
+	rc = sysfs_create_group(&dev->dev.kobj, &ibmveth_attr_group);
+	if (rc) {
+		netdev_err(netdev, "failed to create sysfs attributes rc=%d\n", rc);
+		unregister_netdev(netdev);
+		free_netdev(netdev);
+		return rc;
+	}

[Severity: High]
If userspace brings up the interface immediately after register_netdev()
succeeds, could adapter->work be scheduled before sysfs_create_group() fails?

If this race occurs, unregister_netdev() does not synchronously cancel the
work.

Could the global workqueue execute the pending adapter->work item on freed
memory after free_netdev() is called in this ibmveth_probe() error path?

*

  Good catch. remove() cancels the work, but this probe error path

  did not. Will cancel_work_sync() (and clean pool kobjects) before

  free_netdev() in v4.

*

[Severity: High]
This is a pre-existing issue in older error paths of ibmveth_probe(), but it
is duplicated here: does this error path leak the adapter->rx_buff_pool
kobjects?

Since kobject_put() is not called on the pool kobjects before free_netdev()
is executed, the kobjects remain attached to the VIO device with dangling
pointers to the freed adapter memory.

Could subsequent sysfs accesses to those pool kobjects trigger a
use-after-free?

*

   Yes — that path (and some older probe failure paths) skip

   kobject_put() on the pool objects. I’ll add a common probe

   cleanup helper in v4 so pool kobjects and the reset work are

   always torn down before free_netdev().

*

Thanks,
Mingming