Commit 1580cbcb authored by Jakub Kicinski's avatar Jakub Kicinski
Browse files

net: netdevsim: add some fake page pool use 

Add very basic page pool use so that we can exercise
the netlink uAPI in a selftest.

Page pool gets created on open, destroyed on close.
But we control allocating of a single page thru debugfs.
This page may survive past the page pool itself so that
we can test orphaned page pools.

Link: https://lore.kernel.org/r/20240412141436.828666-2-kuba@kernel.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 77c842ca

drivers/net/netdevsim/netdev.c

+93 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/netdevice.h>

#include <linux/slab.h>

#include <net/netdev_queues.h>

#include <net/page_pool/helpers.h>

#include <net/netlink.h>

#include <net/pkt_cls.h>

#include <net/rtnetlink.h>
@@ -299,6 +300,29 @@ static int nsim_get_iflink(const struct net_device *dev) 
	return iflink;

}



static int nsim_open(struct net_device *dev)

{

	struct netdevsim *ns = netdev_priv(dev);

	struct page_pool_params pp = { 0 };



	pp.pool_size = 128;

	pp.dev = &dev->dev;

	pp.dma_dir = DMA_BIDIRECTIONAL;

	pp.netdev = dev;



	ns->pp = page_pool_create(&pp);

	return PTR_ERR_OR_ZERO(ns->pp);

}



static int nsim_stop(struct net_device *dev)

{

	struct netdevsim *ns = netdev_priv(dev);



	page_pool_destroy(ns->pp);



	return 0;

}



static const struct net_device_ops nsim_netdev_ops = {

	.ndo_start_xmit		= nsim_start_xmit,

	.ndo_set_rx_mode	= nsim_set_rx_mode,
@@ -318,6 +342,8 @@ static const struct net_device_ops nsim_netdev_ops = { 
	.ndo_set_features	= nsim_set_features,

	.ndo_get_iflink		= nsim_get_iflink,

	.ndo_bpf		= nsim_bpf,

	.ndo_open		= nsim_open,

	.ndo_stop		= nsim_stop,

};



static const struct net_device_ops nsim_vf_netdev_ops = {
@@ -378,6 +404,60 @@ static const struct netdev_stat_ops nsim_stat_ops = { 
	.get_base_stats		= nsim_get_base_stats,

};



static ssize_t

nsim_pp_hold_read(struct file *file, char __user *data,

		  size_t count, loff_t *ppos)

{

	struct netdevsim *ns = file->private_data;

	char buf[3] = "n\n";



	if (ns->page)

		buf[0] = 'y';



	return simple_read_from_buffer(data, count, ppos, buf, 2);

}



static ssize_t

nsim_pp_hold_write(struct file *file, const char __user *data,

		   size_t count, loff_t *ppos)

{

	struct netdevsim *ns = file->private_data;

	ssize_t ret;

	bool val;



	ret = kstrtobool_from_user(data, count, &val);

	if (ret)

		return ret;



	rtnl_lock();

	ret = count;

	if (val == !!ns->page)

		goto exit;



	if (!netif_running(ns->netdev) && val) {

		ret = -ENETDOWN;

	} else if (val) {

		ns->page = page_pool_dev_alloc_pages(ns->pp);

		if (!ns->page)

			ret = -ENOMEM;

	} else {

		page_pool_put_full_page(ns->page->pp, ns->page, false);

		ns->page = NULL;

	}

	rtnl_unlock();



exit:

	return count;

}



static const struct file_operations nsim_pp_hold_fops = {

	.open = simple_open,

	.read = nsim_pp_hold_read,

	.write = nsim_pp_hold_write,

	.llseek = generic_file_llseek,

	.owner = THIS_MODULE,

};



static void nsim_setup(struct net_device *dev)

{

	ether_setup(dev);
@@ -485,6 +565,10 @@ nsim_create(struct nsim_dev *nsim_dev, struct nsim_dev_port *nsim_dev_port) 
		err = nsim_init_netdevsim_vf(ns);

	if (err)

		goto err_free_netdev;



	ns->pp_dfs = debugfs_create_file("pp_hold", 0600, nsim_dev_port->ddir,

					 ns, &nsim_pp_hold_fops);



	return ns;



err_free_netdev:
@@ -497,6 +581,8 @@ void nsim_destroy(struct netdevsim *ns) 
	struct net_device *dev = ns->netdev;

	struct netdevsim *peer;



	debugfs_remove(ns->pp_dfs);



	rtnl_lock();

	peer = rtnl_dereference(ns->peer);

	if (peer)
@@ -511,6 +597,13 @@ void nsim_destroy(struct netdevsim *ns) 
	rtnl_unlock();

	if (nsim_dev_port_is_pf(ns->nsim_dev_port))

		nsim_exit_netdevsim(ns);



	/* Put this intentionally late to exercise the orphaning path */

	if (ns->page) {

		page_pool_put_full_page(ns->page->pp, ns->page, false);

		ns->page = NULL;

	}



	free_netdev(dev);

}

drivers/net/netdevsim/netdevsim.h

+4 −0
Original line number Diff line number Diff line
@@ -125,6 +125,10 @@ struct netdevsim { 
		struct debugfs_u32_array dfs_ports[2];

	} udp_ports;



	struct page_pool *pp;

	struct page *page;

	struct dentry *pp_dfs;



	struct nsim_ethtool ethtool;

	struct netdevsim __rcu *peer;

};