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[2a03:2880:ff:74::face:b00c]) by smtp.gmail.com with ESMTPSA id f26-20020aa78b1a000000b006d97f80c4absm10934573pfd.41.2023.12.27.17.46.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Dec 2023 17:46:38 -0800 (PST) From: David Wei To: Jakub Kicinski , Jiri Pirko , Sabrina Dubroca , netdev@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Paolo Abeni Subject: [PATCH net-next v5 2/5] netdevsim: allow two netdevsim ports to be connected Date: Wed, 27 Dec 2023 17:46:30 -0800 Message-Id: <20231228014633.3256862-3-dw@davidwei.uk> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20231228014633.3256862-1-dw@davidwei.uk> References: <20231228014633.3256862-1-dw@davidwei.uk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org 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. During nsim_dev_peer_write(), nsim_dev_list_lock prevents concurrent modifications to nsim_dev and peer's devlink->lock prevents concurrent modifications to the peer's port_list. rtnl_lock ensures netdevices do not change during the critical section where a link is established. The lock order is consistent with other parts that touch netdevsim and should not deadlock. During nsim_dev_peer_read(), RCU read critical section ensures valid values even if stale. Signed-off-by: David Wei --- drivers/net/netdevsim/dev.c | 134 +++++++++++++++++++++++++++--- drivers/net/netdevsim/netdev.c | 6 ++ drivers/net/netdevsim/netdevsim.h | 1 + 3 files changed, 128 insertions(+), 13 deletions(-) diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c index 8d477aa99f94..6d5e4ce08dfd 100644 --- a/drivers/net/netdevsim/dev.c +++ b/drivers/net/netdevsim/dev.c @@ -391,6 +391,124 @@ static const struct file_operations nsim_dev_rate_parent_fops = { .owner = THIS_MODULE, }; +static struct nsim_dev *nsim_dev_find_by_id(unsigned int id) +{ + struct nsim_dev *dev; + + list_for_each_entry(dev, &nsim_dev_list, list) + if (dev->nsim_bus_dev->dev.id == id) + return dev; + + return NULL; +} + +static struct nsim_dev_port * +__nsim_dev_port_lookup(struct nsim_dev *nsim_dev, enum nsim_dev_port_type type, + unsigned int port_index) +{ + struct nsim_dev_port *nsim_dev_port; + + port_index = nsim_dev_port_index(type, port_index); + list_for_each_entry(nsim_dev_port, &nsim_dev->port_list, list) + if (nsim_dev_port->port_index == port_index) + return nsim_dev_port; + 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; + ssize_t ret = 0; + char buf[23]; + + nsim_dev_port = file->private_data; + rcu_read_lock(); + peer = rcu_dereference(nsim_dev_port->ns->peer); + if (!peer) { + rcu_read_unlock(); + return 0; + } + + id = peer->nsim_bus_dev->dev.id; + port = peer->nsim_dev_port->port_index; + ret = scnprintf(buf, sizeof(buf), "%u %u\n", id, port); + ret = simple_read_from_buffer(data, count, ppos, buf, ret); + + rcu_read_unlock(); + return ret; +} + +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_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 is peer netdevsim \"id port\" (uint uint)\n"); + return -EINVAL; + } + + ret = -EINVAL; + mutex_lock(&nsim_dev_list_lock); + peer_dev = nsim_dev_find_by_id(id); + if (!peer_dev) { + pr_err("Peer netdevsim %u does not exist\n", id); + goto out_mutex; + } + + devl_lock(priv_to_devlink(peer_dev)); + rtnl_lock(); + nsim_dev_port = file->private_data; + peer_dev_port = __nsim_dev_port_lookup(peer_dev, NSIM_DEV_PORT_TYPE_PF, + port); + if (!peer_dev_port) { + pr_err("Peer netdevsim %u port %u does not exist\n", id, port); + goto out_devl; + } + + if (nsim_dev_port == peer_dev_port) { + pr_err("Cannot link netdevsim to itself\n"); + goto out_devl; + } + + rcu_assign_pointer(nsim_dev_port->ns->peer, peer_dev_port->ns); + rcu_assign_pointer(peer_dev_port->ns->peer, nsim_dev_port->ns); + ret = count; + +out_devl: + rtnl_unlock(); + devl_unlock(priv_to_devlink(peer_dev)); +out_mutex: + mutex_unlock(&nsim_dev_list_lock); + + return ret; +} + +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) { @@ -421,6 +539,9 @@ 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; } @@ -1704,19 +1825,6 @@ void nsim_drv_remove(struct nsim_bus_dev *nsim_bus_dev) dev_set_drvdata(&nsim_bus_dev->dev, NULL); } -static struct nsim_dev_port * -__nsim_dev_port_lookup(struct nsim_dev *nsim_dev, enum nsim_dev_port_type type, - unsigned int port_index) -{ - struct nsim_dev_port *nsim_dev_port; - - port_index = nsim_dev_port_index(type, port_index); - list_for_each_entry(nsim_dev_port, &nsim_dev->port_list, list) - if (nsim_dev_port->port_index == port_index) - return nsim_dev_port; - return NULL; -} - int nsim_drv_port_add(struct nsim_bus_dev *nsim_bus_dev, enum nsim_dev_port_type type, unsigned int port_index) { diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c index aecaf5f44374..434322f6a565 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); @@ -407,8 +408,13 @@ 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); + if (peer) + RCU_INIT_POINTER(peer->peer, NULL); + RCU_INIT_POINTER(ns->peer, NULL); unregister_netdevice(dev); if (nsim_dev_port_is_pf(ns->nsim_dev_port)) { nsim_macsec_teardown(ns); diff --git a/drivers/net/netdevsim/netdevsim.h b/drivers/net/netdevsim/netdevsim.h index babb61d7790b..24fc3fbda791 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 *