| Message ID | 20210113154550.789244-1-lorenzo@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] usb: gadget: u_ether: support configuring interface names. | expand |
On Thu, Jan 14, 2021 at 12:45:50AM +0900, Lorenzo Colitti wrote: > This patch allows the administrator to configure the interface > name of a function using u_ether (e.g., eem, ncm, rndis). > > Currently, all such interfaces, regardless of function type, are > always called usb0, usb1, etc. This makes it very cumbersome to > use more than one such type at a time, because userspace cannnot > easily tell the interfaces apart and apply the right > configuration to each one. Interface renaming in userspace based > on driver doesn't help, because the interfaces all have the same > driver. Without this patch, doing this require hacks/workarounds > such as setting fixed MAC addresses on the functions, and then > renaming by MAC address, or scraping configfs after each > interface is created to find out what it is. > > Setting the interface name is done by writing to the same > "ifname" configfs attribute that reports the interface name after > the function is bound. The write must contain an interface > pattern such as "usb%d" (which will cause the net core to pick > the next available interface name starting with "usb"). > This patch does not allow writing an exact interface name (as > opposed to a pattern) because if the interface already exists at > bind time, the bind will fail and the whole gadget will fail to > activate. This could be allowed in a future patch. > > For compatibility with current userspace, when reading an ifname > that has not currently been set, the result is still "(unnamed > net_device)". Once a write to ifname happens, then reading ifname > will return whatever was last written. > > Tested by configuring an rndis function and an ncm function on > the same gadget, and writing "rndis%d" to ifname on the rndis > function and "ncm%d" to ifname on the ncm function. When the > gadget was bound, the rndis interface was rndis0 and the ncm > interface was ncm0. > > Signed-off-by: Lorenzo Colitti <lorenzo@google.com> > --- > Documentation/usb/gadget-testing.rst | 30 +++++++-------- > drivers/usb/gadget/function/u_ether.c | 37 +++++++++++++++++-- > drivers/usb/gadget/function/u_ether.h | 12 ++++++ > .../usb/gadget/function/u_ether_configfs.h | 15 +++++++- > 4 files changed, 75 insertions(+), 19 deletions(-) > > diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst > index 2eeb3e9299e4..2085e7b24eeb 100644 > --- a/Documentation/usb/gadget-testing.rst > +++ b/Documentation/usb/gadget-testing.rst > @@ -91,9 +91,9 @@ The ECM function provides these attributes in its function directory: > > and after creating the functions/ecm.<instance name> they contain default > values: qmult is 5, dev_addr and host_addr are randomly selected. > -Except for ifname they can be written to until the function is linked to a > -configuration. The ifname is read-only and contains the name of the interface > -which was assigned by the net core, e. g. usb0. > +The ifname can be written to if the function is not bound. A write must be an > +interface pattern such as "usb%d", which will cause the net core to choose the > +next free usbX interface. By default, it is set to "usb%d". > > Testing the ECM function > ------------------------ > @@ -131,9 +131,9 @@ The ECM subset function provides these attributes in its function directory: > > and after creating the functions/ecm.<instance name> they contain default > values: qmult is 5, dev_addr and host_addr are randomly selected. > -Except for ifname they can be written to until the function is linked to a > -configuration. The ifname is read-only and contains the name of the interface > -which was assigned by the net core, e. g. usb0. > +The ifname can be written to if the function is not bound. A write must be an > +interface pattern such as "usb%d", which will cause the net core to choose the > +next free usbX interface. By default, it is set to "usb%d". > > Testing the ECM subset function > ------------------------------- > @@ -171,9 +171,9 @@ The EEM function provides these attributes in its function directory: > > and after creating the functions/eem.<instance name> they contain default > values: qmult is 5, dev_addr and host_addr are randomly selected. > -Except for ifname they can be written to until the function is linked to a > -configuration. The ifname is read-only and contains the name of the interface > -which was assigned by the net core, e. g. usb0. > +The ifname can be written to if the function is not bound. A write must be an > +interface pattern such as "usb%d", which will cause the net core to choose the > +next free usbX interface. By default, it is set to "usb%d". > > Testing the EEM function > ------------------------ > @@ -453,9 +453,9 @@ The NCM function provides these attributes in its function directory: > > and after creating the functions/ncm.<instance name> they contain default > values: qmult is 5, dev_addr and host_addr are randomly selected. > -Except for ifname they can be written to until the function is linked to a > -configuration. The ifname is read-only and contains the name of the interface > -which was assigned by the net core, e. g. usb0. > +The ifname can be written to if the function is not bound. A write must be an > +interface pattern such as "usb%d", which will cause the net core to choose the > +next free usbX interface. By default, it is set to "usb%d". > > Testing the NCM function > ------------------------ > @@ -591,9 +591,9 @@ The RNDIS function provides these attributes in its function directory: > > and after creating the functions/rndis.<instance name> they contain default > values: qmult is 5, dev_addr and host_addr are randomly selected. > -Except for ifname they can be written to until the function is linked to a > -configuration. The ifname is read-only and contains the name of the interface > -which was assigned by the net core, e. g. usb0. > +The ifname can be written to if the function is not bound. A write must be an > +interface pattern such as "usb%d", which will cause the net core to choose the > +next free usbX interface. By default, it is set to "usb%d". > > Testing the RNDIS function > -------------------------- > diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c > index c019f2b0c0af..a4ade7983402 100644 > --- a/drivers/usb/gadget/function/u_ether.c > +++ b/drivers/usb/gadget/function/u_ether.c > @@ -78,8 +78,9 @@ struct eth_dev { > unsigned long todo; > #define WORK_RX_MEMORY 0 > > - bool zlp; > - bool no_skb_reserve; > + bool zlp:1; > + bool no_skb_reserve:1; > + bool ifname_set:1; Not to be a pain, but "bool var:1"? What's wrong with just a bool itself? gcc is known to have issues with setting/clearing bit fields like this, and there is no size issues here with this device, adding one more byte is just fine. So just add: bool ifname_set; please. thanks, greg k-h
On Thu, Jan 14, 2021 at 1:19 AM Greg KH <gregkh@linuxfoundation.org> wrote: > > - bool zlp; > > - bool no_skb_reserve; > > + bool zlp:1; > > + bool no_skb_reserve:1; > > + bool ifname_set:1; > > Not to be a pain, but "bool var:1"? What's wrong with just a bool > itself? gcc is known to have issues with setting/clearing bit fields > like this, and there is no size issues here with this device, adding one > more byte is just fine. > > So just add: > bool ifname_set; Ack. I guess turning it into a bitfield was premature optimization. Sent out v3 where this is its own boolean.
diff --git a/Documentation/usb/gadget-testing.rst b/Documentation/usb/gadget-testing.rst index 2eeb3e9299e4..2085e7b24eeb 100644 --- a/Documentation/usb/gadget-testing.rst +++ b/Documentation/usb/gadget-testing.rst @@ -91,9 +91,9 @@ The ECM function provides these attributes in its function directory: and after creating the functions/ecm.<instance name> they contain default values: qmult is 5, dev_addr and host_addr are randomly selected. -Except for ifname they can be written to until the function is linked to a -configuration. The ifname is read-only and contains the name of the interface -which was assigned by the net core, e. g. usb0. +The ifname can be written to if the function is not bound. A write must be an +interface pattern such as "usb%d", which will cause the net core to choose the +next free usbX interface. By default, it is set to "usb%d". Testing the ECM function ------------------------ @@ -131,9 +131,9 @@ The ECM subset function provides these attributes in its function directory: and after creating the functions/ecm.<instance name> they contain default values: qmult is 5, dev_addr and host_addr are randomly selected. -Except for ifname they can be written to until the function is linked to a -configuration. The ifname is read-only and contains the name of the interface -which was assigned by the net core, e. g. usb0. +The ifname can be written to if the function is not bound. A write must be an +interface pattern such as "usb%d", which will cause the net core to choose the +next free usbX interface. By default, it is set to "usb%d". Testing the ECM subset function ------------------------------- @@ -171,9 +171,9 @@ The EEM function provides these attributes in its function directory: and after creating the functions/eem.<instance name> they contain default values: qmult is 5, dev_addr and host_addr are randomly selected. -Except for ifname they can be written to until the function is linked to a -configuration. The ifname is read-only and contains the name of the interface -which was assigned by the net core, e. g. usb0. +The ifname can be written to if the function is not bound. A write must be an +interface pattern such as "usb%d", which will cause the net core to choose the +next free usbX interface. By default, it is set to "usb%d". Testing the EEM function ------------------------ @@ -453,9 +453,9 @@ The NCM function provides these attributes in its function directory: and after creating the functions/ncm.<instance name> they contain default values: qmult is 5, dev_addr and host_addr are randomly selected. -Except for ifname they can be written to until the function is linked to a -configuration. The ifname is read-only and contains the name of the interface -which was assigned by the net core, e. g. usb0. +The ifname can be written to if the function is not bound. A write must be an +interface pattern such as "usb%d", which will cause the net core to choose the +next free usbX interface. By default, it is set to "usb%d". Testing the NCM function ------------------------ @@ -591,9 +591,9 @@ The RNDIS function provides these attributes in its function directory: and after creating the functions/rndis.<instance name> they contain default values: qmult is 5, dev_addr and host_addr are randomly selected. -Except for ifname they can be written to until the function is linked to a -configuration. The ifname is read-only and contains the name of the interface -which was assigned by the net core, e. g. usb0. +The ifname can be written to if the function is not bound. A write must be an +interface pattern such as "usb%d", which will cause the net core to choose the +next free usbX interface. By default, it is set to "usb%d". Testing the RNDIS function -------------------------- diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index c019f2b0c0af..a4ade7983402 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -78,8 +78,9 @@ struct eth_dev { unsigned long todo; #define WORK_RX_MEMORY 0 - bool zlp; - bool no_skb_reserve; + bool zlp:1; + bool no_skb_reserve:1; + bool ifname_set:1; u8 host_mac[ETH_ALEN]; u8 dev_mac[ETH_ALEN]; }; @@ -1004,15 +1005,45 @@ EXPORT_SYMBOL_GPL(gether_get_qmult); int gether_get_ifname(struct net_device *net, char *name, int len) { + struct eth_dev *dev = netdev_priv(net); int ret; rtnl_lock(); - ret = scnprintf(name, len, "%s\n", netdev_name(net)); + ret = scnprintf(name, len, "%s\n", + dev->ifname_set ? net->name : netdev_name(net)); rtnl_unlock(); return ret; } EXPORT_SYMBOL_GPL(gether_get_ifname); +int gether_set_ifname(struct net_device *net, const char *name, int len) +{ + struct eth_dev *dev = netdev_priv(net); + char tmp[IFNAMSIZ]; + const char *p; + + if (name[len - 1] == '\n') + len--; + + if (len >= sizeof(tmp)) + return -E2BIG; + + strscpy(tmp, name, len + 1); + if (!dev_valid_name(tmp)) + return -EINVAL; + + /* Require exactly one %d, so binding will not fail with EEXIST. */ + p = strchr(name, '%'); + if (!p || p[1] != 'd' || strchr(p + 2, '%')) + return -EINVAL; + + strncpy(net->name, tmp, sizeof(net->name)); + dev->ifname_set = true; + + return 0; +} +EXPORT_SYMBOL_GPL(gether_set_ifname); + /* * gether_cleanup - remove Ethernet-over-USB device * Context: may sleep diff --git a/drivers/usb/gadget/function/u_ether.h b/drivers/usb/gadget/function/u_ether.h index 10dd640684e2..40144546d1b0 100644 --- a/drivers/usb/gadget/function/u_ether.h +++ b/drivers/usb/gadget/function/u_ether.h @@ -244,6 +244,18 @@ unsigned gether_get_qmult(struct net_device *net); */ int gether_get_ifname(struct net_device *net, char *name, int len); +/** + * gether_set_ifname - set an ethernet-over-usb link interface name + * @net: device representing this link + * @name: new interface name + * @len: length of @name + * + * This sets the interface name of this ethernet-over-usb link. + * A single terminating newline, if any, is ignored. + * Returns zero on success, else negative errno. + */ +int gether_set_ifname(struct net_device *net, const char *name, int len); + void gether_cleanup(struct eth_dev *dev); /* connect/disconnect is handled by individual functions */ diff --git a/drivers/usb/gadget/function/u_ether_configfs.h b/drivers/usb/gadget/function/u_ether_configfs.h index bd92b5703013..3dfb460908fa 100644 --- a/drivers/usb/gadget/function/u_ether_configfs.h +++ b/drivers/usb/gadget/function/u_ether_configfs.h @@ -148,7 +148,20 @@ out: \ return ret; \ } \ \ - CONFIGFS_ATTR_RO(_f_##_opts_, ifname) + 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); \ + int ret = -EBUSY; \ + \ + mutex_lock(&opts->lock); \ + if (!opts->refcnt) \ + ret = gether_set_ifname(opts->net, page, len); \ + mutex_unlock(&opts->lock); \ + return ret ?: len; \ + } \ + \ + CONFIGFS_ATTR(_f_##_opts_, ifname) #define USB_ETHER_CONFIGFS_ITEM_ATTR_U8_RW(_f_, _n_) \ static ssize_t _f_##_opts_##_n_##_show(struct config_item *item,\
This patch allows the administrator to configure the interface name of a function using u_ether (e.g., eem, ncm, rndis). Currently, all such interfaces, regardless of function type, are always called usb0, usb1, etc. This makes it very cumbersome to use more than one such type at a time, because userspace cannnot easily tell the interfaces apart and apply the right configuration to each one. Interface renaming in userspace based on driver doesn't help, because the interfaces all have the same driver. Without this patch, doing this require hacks/workarounds such as setting fixed MAC addresses on the functions, and then renaming by MAC address, or scraping configfs after each interface is created to find out what it is. Setting the interface name is done by writing to the same "ifname" configfs attribute that reports the interface name after the function is bound. The write must contain an interface pattern such as "usb%d" (which will cause the net core to pick the next available interface name starting with "usb"). This patch does not allow writing an exact interface name (as opposed to a pattern) because if the interface already exists at bind time, the bind will fail and the whole gadget will fail to activate. This could be allowed in a future patch. For compatibility with current userspace, when reading an ifname that has not currently been set, the result is still "(unnamed net_device)". Once a write to ifname happens, then reading ifname will return whatever was last written. Tested by configuring an rndis function and an ncm function on the same gadget, and writing "rndis%d" to ifname on the rndis function and "ncm%d" to ifname on the ncm function. When the gadget was bound, the rndis interface was rndis0 and the ncm interface was ncm0. Signed-off-by: Lorenzo Colitti <lorenzo@google.com> --- Documentation/usb/gadget-testing.rst | 30 +++++++-------- drivers/usb/gadget/function/u_ether.c | 37 +++++++++++++++++-- drivers/usb/gadget/function/u_ether.h | 12 ++++++ .../usb/gadget/function/u_ether_configfs.h | 15 +++++++- 4 files changed, 75 insertions(+), 19 deletions(-)