netdev - [PATCH net-next] net: netdevsim: Support setting dev->perm

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Message-Id: <20250203-netdevsim-perm_addr-v1-1-10084bc93044@redhat.com>
Date: Mon, 03 Feb 2025 18:21:24 +0100
From: Toke Høiland-Jørgensen <toke@...hat.com>
To: Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>
Cc: netdev@...r.kernel.org, 
 Toke Høiland-Jørgensen <toke@...hat.com>
Subject: [PATCH net-next] net: netdevsim: Support setting dev->perm_addr

Network management daemons that match on the device permanent address
currently have no virtual interface types to test against.
NetworkManager, in particular, has carried an out of tree patch to set
the permanent address on netdevsim devices to use in its CI for this
purpose.

To support this use case, add a debugfs file for netdevsim to set the
permanent address to an arbitrary value.

Signed-off-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
 drivers/net/netdevsim/netdev.c    | 44 +++++++++++++++++++++++++++++++++++++++
 drivers/net/netdevsim/netdevsim.h |  1 +
 2 files changed, 45 insertions(+)

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index 42f247cbdceecbadf27f7090c030aa5bd240c18a..3a7fcc32901c754eadf7d6ea43cd0ddc29586cf9 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -782,6 +782,47 @@ static const struct file_operations nsim_qreset_fops = {
 	.owner = THIS_MODULE,
 };
 
+static ssize_t
+nsim_permaddr_write(struct file *file, const char __user *data,
+		    size_t count, loff_t *ppos)
+{
+	struct netdevsim *ns = file->private_data;
+	u8 eth_addr[ETH_ALEN];
+	char buf[32];
+	ssize_t ret;
+
+	if (count >= sizeof(buf))
+		return -EINVAL;
+	if (copy_from_user(buf, data, count))
+		return -EFAULT;
+	buf[count] = '\0';
+
+	ret = sscanf(buf, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+		     &eth_addr[0], &eth_addr[1], &eth_addr[2],
+		     &eth_addr[3], &eth_addr[4], &eth_addr[5]);
+	if (ret != 6)
+		return -EINVAL;
+
+	rtnl_lock();
+	if (netif_running(ns->netdev)) {
+		ret = -EBUSY;
+		goto exit_unlock;
+	}
+
+	memcpy(ns->netdev->perm_addr, eth_addr, sizeof(eth_addr));
+
+	ret = count;
+exit_unlock:
+	rtnl_unlock();
+	return ret;
+}
+
+static const struct file_operations nsim_permaddr_fops = {
+	.open = simple_open,
+	.write = nsim_permaddr_write,
+	.owner = THIS_MODULE,
+};
+
 static ssize_t
 nsim_pp_hold_read(struct file *file, char __user *data,
 		  size_t count, loff_t *ppos)
@@ -997,6 +1038,9 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
 	ns->qr_dfs = debugfs_create_file("queue_reset", 0200,
 					 nsim_dev_port->ddir, ns,
 					 &nsim_qreset_fops);
+	ns->permaddr_dfs = debugfs_create_file("perm_addr", 0200,
+					       nsim_dev_port->ddir, ns,
+					       &nsim_permaddr_fops);
 
 	return ns;
 
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index dcf073bc4802e7f7f8c14a2b8d94d24cd31f1f7b..fffec5dbf80759240a323f7c3630c79c5c68faec 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -140,6 +140,7 @@ struct netdevsim {
 	struct page *page;
 	struct dentry *pp_dfs;
 	struct dentry *qr_dfs;
+	struct dentry *permaddr_dfs;
 
 	struct nsim_ethtool ethtool;
 	struct netdevsim __rcu *peer;

---
base-commit: 0ad9617c78acbc71373fb341a6f75d4012b01d69
change-id: 20250128-netdevsim-perm_addr-5fca47a08157