diff mbox series

[net-next,v2,1/3] netdevsim: allow two netdevsim ports to be connected

Message ID 20231210010448.816126-2-dw@davidwei.uk (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series netdevsim: link and forward skbs between ports | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1115 this patch: 1115
netdev/cc_maintainers success CCed 4 of 4 maintainers
netdev/build_clang success Errors and warnings before: 1142 this patch: 1142
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 1142 this patch: 1142
netdev/checkpatch warning WARNING: From:/Signed-off-by: email address mismatch: 'From: David Wei <davidhwei@meta.com>' != 'Signed-off-by: David Wei <dw@davidwei.uk>' WARNING: Missing a blank line after declarations
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

David Wei Dec. 10, 2023, 1:04 a.m. UTC 
From: David Wei <davidhwei@meta.com>

Add a debugfs file in
/sys/kernel/debug/netdevsim/netdevsimN/ports/A/peer

Writing "M B" to this file will link port A of netdevsim N with port B of
netdevsim M.

Reading this file will return the linked netdevsim id and port, if any.

Signed-off-by: David Wei <dw@davidwei.uk>
---
 drivers/net/netdevsim/bus.c       | 10 ++++
 drivers/net/netdevsim/dev.c       | 85 +++++++++++++++++++++++++++++++
 drivers/net/netdevsim/netdev.c    |  6 +++
 drivers/net/netdevsim/netdevsim.h |  3 ++
 4 files changed, 104 insertions(+)

Comments

Jakub Kicinski Dec. 12, 2023, 8:24 p.m. UTC | #1 
On Sat,  9 Dec 2023 17:04:46 -0800 David Wei wrote:
> diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
> index bcbc1e19edde..3e4378e9dbee 100644
> --- a/drivers/net/netdevsim/bus.c
> +++ b/drivers/net/netdevsim/bus.c
> @@ -364,3 +364,13 @@ void nsim_bus_exit(void)
>  	driver_unregister(&nsim_driver);
>  	bus_unregister(&nsim_bus);
>  }
> +
> +struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id)

nit: s/get/find/ get sometimes implied taking a reference 

> +{
> +	struct nsim_bus_dev *nsim_bus_dev;

new line here, please checkpatch --strict

> +	list_for_each_entry(nsim_bus_dev, &nsim_bus_dev_list, list) {
> +		if (nsim_bus_dev->dev.id == id)
> +			return nsim_bus_dev;

You must assume some lock is being held so that you can walk the list
and return a meaningful value? :) Please figure out what caller has to
hold and add an appropriate lockdep assert here.

> +	}
> +	return NULL;
> +}

> +static ssize_t nsim_dev_peer_read(struct file *file, char __user *data,
> +				  size_t count, loff_t *ppos)
> +{
> +	struct nsim_dev_port *nsim_dev_port;
> +	struct netdevsim *peer;
> +	unsigned int id, port;
> +	char buf[23];
> +	ssize_t len;
> +
> +	nsim_dev_port = file->private_data;
> +	rcu_read_lock();
> +	peer = rcu_dereference(nsim_dev_port->ns->peer);
> +	if (!peer) {
> +		len = scnprintf(buf, sizeof(buf), "\n");

Why not return 0?

> +		goto out;
> +	}
> +
> +	id = peer->nsim_bus_dev->dev.id;
> +	port = peer->nsim_dev_port->port_index;
> +	len = scnprintf(buf, sizeof(buf), "%u %u\n", id, port);
> +
> +out:
> +	rcu_read_unlock();
> +	return simple_read_from_buffer(data, count, ppos, buf, len);
> +}

> @@ -417,3 +418,5 @@ struct nsim_bus_dev {
>  
>  int nsim_bus_init(void);
>  void nsim_bus_exit(void);
> +
> +struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id);

nit: let this go before the module init/exit funcs, 3 lines up
David Wei Dec. 13, 2023, 12:37 a.m. UTC | #2 
On 2023-12-12 12:24, Jakub Kicinski wrote:
> On Sat,  9 Dec 2023 17:04:46 -0800 David Wei wrote:
>> diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
>> index bcbc1e19edde..3e4378e9dbee 100644
>> --- a/drivers/net/netdevsim/bus.c
>> +++ b/drivers/net/netdevsim/bus.c
>> @@ -364,3 +364,13 @@ void nsim_bus_exit(void)
>>  	driver_unregister(&nsim_driver);
>>  	bus_unregister(&nsim_bus);
>>  }
>> +
>> +struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id)
> 
> nit: s/get/find/ get sometimes implied taking a reference 

Will do.

> 
>> +{
>> +	struct nsim_bus_dev *nsim_bus_dev;
> 
> new line here, please checkpatch --strict

Sorry, will remember to do this next time.

> 
>> +	list_for_each_entry(nsim_bus_dev, &nsim_bus_dev_list, list) {
>> +		if (nsim_bus_dev->dev.id == id)
>> +			return nsim_bus_dev;
> 
> You must assume some lock is being held so that you can walk the list
> and return a meaningful value? :) Please figure out what caller has to
> hold and add an appropriate lockdep assert here.

Will address.

> 
>> +	}
>> +	return NULL;
>> +}
> 
>> +static ssize_t nsim_dev_peer_read(struct file *file, char __user *data,
>> +				  size_t count, loff_t *ppos)
>> +{
>> +	struct nsim_dev_port *nsim_dev_port;
>> +	struct netdevsim *peer;
>> +	unsigned int id, port;
>> +	char buf[23];
>> +	ssize_t len;
>> +
>> +	nsim_dev_port = file->private_data;
>> +	rcu_read_lock();
>> +	peer = rcu_dereference(nsim_dev_port->ns->peer);
>> +	if (!peer) {
>> +		len = scnprintf(buf, sizeof(buf), "\n");
> 
> Why not return 0?

No reason, wasn't sure what the norm is.

> 
>> +		goto out;
>> +	}
>> +
>> +	id = peer->nsim_bus_dev->dev.id;
>> +	port = peer->nsim_dev_port->port_index;
>> +	len = scnprintf(buf, sizeof(buf), "%u %u\n", id, port);
>> +
>> +out:
>> +	rcu_read_unlock();
>> +	return simple_read_from_buffer(data, count, ppos, buf, len);
>> +}
> 
>> @@ -417,3 +418,5 @@ struct nsim_bus_dev {
>>  
>>  int nsim_bus_init(void);
>>  void nsim_bus_exit(void);
>> +
>> +struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id);
> 
> nit: let this go before the module init/exit funcs, 3 lines up

Will address.
diff mbox series

Patch

diff --git a/drivers/net/netdevsim/bus.c b/drivers/net/netdevsim/bus.c
index bcbc1e19edde..3e4378e9dbee 100644
--- a/drivers/net/netdevsim/bus.c
+++ b/drivers/net/netdevsim/bus.c
@@ -364,3 +364,13 @@  void nsim_bus_exit(void)
 	driver_unregister(&nsim_driver);
 	bus_unregister(&nsim_bus);
 }
+
+struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id)
+{
+	struct nsim_bus_dev *nsim_bus_dev;
+	list_for_each_entry(nsim_bus_dev, &nsim_bus_dev_list, list) {
+		if (nsim_bus_dev->dev.id == id)
+			return nsim_bus_dev;
+	}
+	return NULL;
+}
diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index b4d3b9cde8bd..7af219ff6fa9 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -388,6 +388,88 @@  static const struct file_operations nsim_dev_rate_parent_fops = {
 	.owner = THIS_MODULE,
 };
 
+static ssize_t nsim_dev_peer_read(struct file *file, char __user *data,
+				  size_t count, loff_t *ppos)
+{
+	struct nsim_dev_port *nsim_dev_port;
+	struct netdevsim *peer;
+	unsigned int id, port;
+	char buf[23];
+	ssize_t len;
+
+	nsim_dev_port = file->private_data;
+	rcu_read_lock();
+	peer = rcu_dereference(nsim_dev_port->ns->peer);
+	if (!peer) {
+		len = scnprintf(buf, sizeof(buf), "\n");
+		goto out;
+	}
+
+	id = peer->nsim_bus_dev->dev.id;
+	port = peer->nsim_dev_port->port_index;
+	len = scnprintf(buf, sizeof(buf), "%u %u\n", id, port);
+
+out:
+	rcu_read_unlock();
+	return simple_read_from_buffer(data, count, ppos, buf, len);
+}
+
+static ssize_t nsim_dev_peer_write(struct file *file,
+				   const char __user *data,
+				   size_t count, loff_t *ppos)
+{
+	struct nsim_dev_port *nsim_dev_port, *peer_dev_port;
+	struct nsim_bus_dev *peer_bus_dev;
+	struct nsim_dev *peer_dev;
+	unsigned int id, port;
+	char buf[22];
+	ssize_t ret;
+
+	if (count >= sizeof(buf))
+		return -ENOSPC;
+
+	ret = copy_from_user(buf, data, count);
+	if (ret)
+		return -EFAULT;
+	buf[count] = '\0';
+
+	ret = sscanf(buf, "%u %u", &id, &port);
+	if (ret != 2) {
+		pr_err("Format for adding a peer is \"id port\" (uint uint)");
+		return -EINVAL;
+	}
+
+	/* invalid netdevsim id */
+	peer_bus_dev = nsim_bus_dev_get(id);
+	if (!peer_bus_dev)
+		return -EINVAL;
+
+	/* cannot link to self */
+	nsim_dev_port = file->private_data;
+	if (nsim_dev_port->ns->nsim_bus_dev == peer_bus_dev &&
+	    nsim_dev_port->port_index == port)
+		return -EINVAL;
+
+	peer_dev = dev_get_drvdata(&peer_bus_dev->dev);
+	list_for_each_entry(peer_dev_port, &peer_dev->port_list, list) {
+		if (peer_dev_port->port_index != port)
+			continue;
+		rcu_assign_pointer(nsim_dev_port->ns->peer, peer_dev_port->ns);
+		rcu_assign_pointer(peer_dev_port->ns->peer, nsim_dev_port->ns);
+		return count;
+	}
+
+	return -EINVAL;
+}
+
+static const struct file_operations nsim_dev_peer_fops = {
+	.open = simple_open,
+	.read = nsim_dev_peer_read,
+	.write = nsim_dev_peer_write,
+	.llseek = generic_file_llseek,
+	.owner = THIS_MODULE,
+};
+
 static int nsim_dev_port_debugfs_init(struct nsim_dev *nsim_dev,
 				      struct nsim_dev_port *nsim_dev_port)
 {
@@ -418,6 +500,9 @@  static int nsim_dev_port_debugfs_init(struct nsim_dev *nsim_dev,
 	}
 	debugfs_create_symlink("dev", nsim_dev_port->ddir, dev_link_name);
 
+	debugfs_create_file("peer", 0600, nsim_dev_port->ddir,
+			    nsim_dev_port, &nsim_dev_peer_fops);
+
 	return 0;
 }
 
diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index aecaf5f44374..e290c54b0e70 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -388,6 +388,7 @@  nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
 	ns->nsim_dev = nsim_dev;
 	ns->nsim_dev_port = nsim_dev_port;
 	ns->nsim_bus_dev = nsim_dev->nsim_bus_dev;
+	RCU_INIT_POINTER(ns->peer, NULL);
 	SET_NETDEV_DEV(dev, &ns->nsim_bus_dev->dev);
 	SET_NETDEV_DEVLINK_PORT(dev, &nsim_dev_port->devlink_port);
 	nsim_ethtool_init(ns);
@@ -407,9 +408,14 @@  nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port)
 void nsim_destroy(struct netdevsim *ns)
 {
 	struct net_device *dev = ns->netdev;
+	struct netdevsim *peer;
 
 	rtnl_lock();
+	peer = rtnl_dereference(ns->peer);
+	RCU_INIT_POINTER(ns->peer, NULL);
 	unregister_netdevice(dev);
+	if (peer)
+		RCU_INIT_POINTER(peer->peer, NULL);
 	if (nsim_dev_port_is_pf(ns->nsim_dev_port)) {
 		nsim_macsec_teardown(ns);
 		nsim_ipsec_teardown(ns);
diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h
index 028c825b86db..2601c3ad1d17 100644
--- a/drivers/net/netdevsim/netdevsim.h
+++ b/drivers/net/netdevsim/netdevsim.h
@@ -125,6 +125,7 @@  struct netdevsim {
 	} udp_ports;
 
 	struct nsim_ethtool ethtool;
+	struct netdevsim __rcu *peer;
 };
 
 struct netdevsim *
@@ -417,3 +418,5 @@  struct nsim_bus_dev {
 
 int nsim_bus_init(void);
 void nsim_bus_exit(void);
+
+struct nsim_bus_dev *nsim_bus_dev_get(unsigned int id);