From e065c6a7e46c2ee9c677fdbf50035323d2de1215 Mon Sep 17 00:00:00 2001 From: Kuen-Han Tsai Date: Tue, 30 Dec 2025 18:13:14 +0800 Subject: [PATCH] usb: gadget: u_ether: add gether_opts for config caching Currently, the net_device is allocated when the function instance is created (e.g., in ncm_alloc_inst()). While this allows userspace to configure the device early, it decouples the net_device lifecycle from the actual USB connection state (bind/unbind). The goal is to defer net_device creation to the bind callback to properly align the lifecycle with its parent gadget device. However, deferring net_device allocation would prevent userspace from configuring parameters (like interface name or MAC address) before the net_device exists. Introduce a new structure, struct gether_opts, associated with the usb_function_instance, to cache settings independently of the net_device. These settings include the interface name pattern, MAC addresses (device and host), queue multiplier, and address assignment type. New helper functions are added: - gether_setup_opts_default(): Initializes struct gether_opts with defaults, including random MAC addresses. - gether_apply_opts(): Applies the cached options from a struct gether_opts to a valid net_device. To expose these options to userspace, new configfs macros (USB_ETHER_OPTS_ITEM and USB_ETHER_OPTS_ATTR_*) are defined in u_ether_configfs.h. These attributes are part of the function instance's configfs group. This refactoring is a preparatory step. It allows the subsequent patch to safely move the net_device allocation from the instance creation phase to the bind phase without losing the ability to pre-configure the interface via configfs. Signed-off-by: Kuen-Han Tsai Link: https://patch.msgid.link/20251230-ncm-refactor-v1-1-793e347bc7a7@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_ether.c | 30 +++ drivers/usb/gadget/function/u_ether.h | 28 +++ .../usb/gadget/function/u_ether_configfs.h | 176 ++++++++++++++++++ 3 files changed, 234 insertions(+) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index f58590bf5e02f..745ed2c212e3a 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -1039,6 +1039,36 @@ int gether_set_ifname(struct net_device *net, const char *name, int len) } EXPORT_SYMBOL_GPL(gether_set_ifname); +void gether_setup_opts_default(struct gether_opts *opts, const char *name) +{ + opts->qmult = QMULT_DEFAULT; + snprintf(opts->name, sizeof(opts->name), "%s%%d", name); + eth_random_addr(opts->dev_mac); + opts->addr_assign_type = NET_ADDR_RANDOM; + eth_random_addr(opts->host_mac); +} +EXPORT_SYMBOL_GPL(gether_setup_opts_default); + +void gether_apply_opts(struct net_device *net, struct gether_opts *opts) +{ + struct eth_dev *dev = netdev_priv(net); + + dev->qmult = opts->qmult; + + if (opts->ifname_set) { + strscpy(net->name, opts->name, sizeof(net->name)); + dev->ifname_set = true; + } + + memcpy(dev->host_mac, opts->host_mac, sizeof(dev->host_mac)); + + if (opts->addr_assign_type == NET_ADDR_SET) { + memcpy(dev->dev_mac, opts->dev_mac, sizeof(dev->dev_mac)); + net->addr_assign_type = opts->addr_assign_type; + } +} +EXPORT_SYMBOL_GPL(gether_apply_opts); + void gether_suspend(struct gether *link) { struct eth_dev *dev = link->ioport; diff --git a/drivers/usb/gadget/function/u_ether.h b/drivers/usb/gadget/function/u_ether.h index 34be220cef77c..63a0240df4d74 100644 --- a/drivers/usb/gadget/function/u_ether.h +++ b/drivers/usb/gadget/function/u_ether.h @@ -38,6 +38,31 @@ struct eth_dev; +/** + * struct gether_opts - Options for Ethernet gadget function instances + * @name: Pattern for the network interface name (e.g., "usb%d"). + * Used to generate the net device name. + * @qmult: Queue length multiplier for high/super speed. + * @host_mac: The MAC address to be used by the host side. + * @dev_mac: The MAC address to be used by the device side. + * @ifname_set: True if the interface name pattern has been set by userspace. + * @addr_assign_type: The method used for assigning the device MAC address + * (e.g., NET_ADDR_RANDOM, NET_ADDR_SET). + * + * This structure caches network-related settings provided through configfs + * before the net_device is fully instantiated. This allows for early + * configuration while deferring net_device allocation until the function + * is bound. + */ +struct gether_opts { + char name[IFNAMSIZ]; + unsigned int qmult; + u8 host_mac[ETH_ALEN]; + u8 dev_mac[ETH_ALEN]; + bool ifname_set; + unsigned char addr_assign_type; +}; + /* * This represents the USB side of an "ethernet" link, managed by a USB * function which provides control and (maybe) framing. Two functions @@ -259,6 +284,9 @@ int gether_set_ifname(struct net_device *net, const char *name, int len); void gether_cleanup(struct eth_dev *dev); +void gether_setup_opts_default(struct gether_opts *opts, const char *name); +void gether_apply_opts(struct net_device *net, struct gether_opts *opts); + void gether_suspend(struct gether *link); void gether_resume(struct gether *link); diff --git a/drivers/usb/gadget/function/u_ether_configfs.h b/drivers/usb/gadget/function/u_ether_configfs.h index 51f0d79e5eca4..39d3a261496d9 100644 --- a/drivers/usb/gadget/function/u_ether_configfs.h +++ b/drivers/usb/gadget/function/u_ether_configfs.h @@ -13,6 +13,12 @@ #ifndef __U_ETHER_CONFIGFS_H #define __U_ETHER_CONFIGFS_H +#include +#include +#include +#include +#include + #define USB_ETHERNET_CONFIGFS_ITEM(_f_) \ static void _f_##_attr_release(struct config_item *item) \ { \ @@ -197,4 +203,174 @@ out: \ \ CONFIGFS_ATTR(_f_##_opts_, _n_) +#define USB_ETHER_OPTS_ITEM(_f_) \ + static void _f_##_attr_release(struct config_item *item) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + \ + usb_put_function_instance(&opts->func_inst); \ + } \ + \ + static struct configfs_item_operations _f_##_item_ops = { \ + .release = _f_##_attr_release, \ + } + +#define USB_ETHER_OPTS_ATTR_DEV_ADDR(_f_) \ + static ssize_t _f_##_opts_dev_addr_show(struct config_item *item, \ + char *page) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + \ + guard(mutex)(&opts->lock); \ + return sysfs_emit(page, "%pM\n", opts->net_opts.dev_mac); \ + } \ + \ + static ssize_t _f_##_opts_dev_addr_store(struct config_item *item, \ + const char *page, size_t len) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + u8 new_addr[ETH_ALEN]; \ + const char *p = page; \ + \ + guard(mutex)(&opts->lock); \ + if (opts->refcnt) \ + return -EBUSY; \ + \ + for (int i = 0; i < ETH_ALEN; i++) { \ + unsigned char num; \ + if ((*p == '.') || (*p == ':')) \ + p++; \ + num = hex_to_bin(*p++) << 4; \ + num |= hex_to_bin(*p++); \ + new_addr[i] = num; \ + } \ + if (!is_valid_ether_addr(new_addr)) \ + return -EINVAL; \ + memcpy(opts->net_opts.dev_mac, new_addr, ETH_ALEN); \ + opts->net_opts.addr_assign_type = NET_ADDR_SET; \ + return len; \ + } \ + \ + CONFIGFS_ATTR(_f_##_opts_, dev_addr) + +#define USB_ETHER_OPTS_ATTR_HOST_ADDR(_f_) \ + static ssize_t _f_##_opts_host_addr_show(struct config_item *item, \ + char *page) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + \ + guard(mutex)(&opts->lock); \ + return sysfs_emit(page, "%pM\n", opts->net_opts.host_mac); \ + } \ + \ + static ssize_t _f_##_opts_host_addr_store(struct config_item *item, \ + const char *page, size_t len) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + u8 new_addr[ETH_ALEN]; \ + const char *p = page; \ + \ + guard(mutex)(&opts->lock); \ + if (opts->refcnt) \ + return -EBUSY; \ + \ + for (int i = 0; i < ETH_ALEN; i++) { \ + unsigned char num; \ + if ((*p == '.') || (*p == ':')) \ + p++; \ + num = hex_to_bin(*p++) << 4; \ + num |= hex_to_bin(*p++); \ + new_addr[i] = num; \ + } \ + if (!is_valid_ether_addr(new_addr)) \ + return -EINVAL; \ + memcpy(opts->net_opts.host_mac, new_addr, ETH_ALEN); \ + return len; \ + } \ + \ + CONFIGFS_ATTR(_f_##_opts_, host_addr) + +#define USB_ETHER_OPTS_ATTR_QMULT(_f_) \ + static ssize_t _f_##_opts_qmult_show(struct config_item *item, \ + char *page) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + \ + guard(mutex)(&opts->lock); \ + return sysfs_emit(page, "%u\n", opts->net_opts.qmult); \ + } \ + \ + static ssize_t _f_##_opts_qmult_store(struct config_item *item, \ + const char *page, size_t len) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + u32 val; \ + int ret; \ + \ + guard(mutex)(&opts->lock); \ + if (opts->refcnt) \ + return -EBUSY; \ + \ + ret = kstrtou32(page, 0, &val); \ + if (ret) \ + return ret; \ + \ + opts->net_opts.qmult = val; \ + return len; \ + } \ + \ + CONFIGFS_ATTR(_f_##_opts_, qmult) + +#define USB_ETHER_OPTS_ATTR_IFNAME(_f_) \ + static ssize_t _f_##_opts_ifname_show(struct config_item *item, \ + char *page) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + const char *name; \ + \ + guard(mutex)(&opts->lock); \ + rtnl_lock(); \ + if (opts->net_opts.ifname_set) \ + name = opts->net_opts.name; \ + else if (opts->net) \ + name = netdev_name(opts->net); \ + else \ + name = "(inactive net_device)"; \ + rtnl_unlock(); \ + return sysfs_emit(page, "%s\n", name); \ + } \ + \ + static ssize_t _f_##_opts_ifname_store(struct config_item *item, \ + const char *page, size_t len) \ + { \ + struct f_##_f_##_opts *opts = to_f_##_f_##_opts(item); \ + char tmp[IFNAMSIZ]; \ + const char *p; \ + size_t c_len = len; \ + \ + if (c_len > 0 && page[c_len - 1] == '\n') \ + c_len--; \ + \ + if (c_len >= sizeof(tmp)) \ + return -E2BIG; \ + \ + strscpy(tmp, page, c_len + 1); \ + if (!dev_valid_name(tmp)) \ + return -EINVAL; \ + \ + /* Require exactly one %d */ \ + p = strchr(tmp, '%'); \ + if (!p || p[1] != 'd' || strchr(p + 2, '%')) \ + return -EINVAL; \ + \ + guard(mutex)(&opts->lock); \ + if (opts->refcnt) \ + return -EBUSY; \ + strscpy(opts->net_opts.name, tmp, sizeof(opts->net_opts.name)); \ + opts->net_opts.ifname_set = true; \ + return len; \ + } \ + \ + CONFIGFS_ATTR(_f_##_opts_, ifname) + #endif /* __U_ETHER_CONFIGFS_H */ -- 2.47.3