[PATCH 2 2/4] net ethernet introduce mac_la_ap helper
From: arnd@arndb.de (Arnd Bergmann)
Date: 2012-07-02 16:12:56
Also in:
linux-omap
On Monday 02 July 2012, Andy Green wrote:
From: Andy Green <redacted> This introduces a small helper in net/ethernet, which registers a network notifier on init, and accepts registrations of expected asynchronously- probed network device paths (like, "usb1/1-1/1-1.1/1-1.1:1.0") and the MAC that is needed to be assigned to the device when it appears. This allows platform code to enforce valid, consistent MAC addresses on to devices that have not been probed at boot-time, but due to being wired on the board are always present at the same interface. It has been tested with USB and SDIO probed devices. To make use of this safely you also need to make sure that any drivers that may compete for the bus ordinal you are using (eg, mUSB and ehci in Panda case) are loaded in a deterministic order. At registration it makes a copy of the incoming data, so the data may be __initdata or otherwise transitory. Registration can be called multiple times so registrations from Device Tree and platform may be mixed. Since it needs to be called quite early in boot and there is no lifecycle for what it does, it could not be modular and is not a driver. Via suggestions from Arnd Bergmann and Tony Lindgren. Signed-off-by: Andy Green <redacted>
Yes, looks good to me in principle. It needs to get sent to the linux-kernel and netdev mailing lists for review though. A few small comments.
quoted hunk ↗ jump to hunk
include/net/mac-la-ap.h | 28 ++++++++ net/Kconfig | 14 ++++ net/ethernet/Makefile | 2 + net/ethernet/mac-la-ap.c | 165 ++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 209 insertions(+) create mode 100644 include/net/mac-la-ap.h create mode 100644 net/ethernet/mac-la-ap.cdiff --git a/include/net/mac-la-ap.h b/include/net/mac-la-ap.h new file mode 100644 index 0000000..d5189b5 --- /dev/null +++ b/include/net/mac-la-ap.h@@ -0,0 +1,28 @@ +/* + * mac-la-ap.h: Locally Administered MAC address for Async probed devices + */
I find the name a bit non-obvious, not sure if we can come up with the perfect one. How about mac-platform?
quoted hunk ↗ jump to hunk
+/** + * mac_la_ap_register_device_macs - add an array of device path to monitor + * and MAC to apply when the network device + * at the device path appears + * @macs: array of struct mac_la_ap terminated by entry with NULL device_path + */ +int mac_la_ap_register_device_macs(const struct mac_la_ap *macs); +diff --git a/net/Kconfig b/net/Kconfig index 245831b..76ba70e 100644 --- a/net/Kconfig +++ b/net/Kconfig@@ -335,6 +335,20 @@ source "net/caif/Kconfig" source "net/ceph/Kconfig" source "net/nfc/Kconfig" +config MAC_LA_AP + bool "Locally Administered MAC for Aysnchronously Probed devices" + ---help--- + This helper allows platforms to mandate a locally-administered + sythesized MAC address for network devices that are on asynchronously- + probed buses like USB or SDIO. This is necessary when the board has + these network assets but no arrangements for storing or setting the + MAC address of the network asset (nor any official MAC address + reserved for the device). In that case, seen in Panda and other + boards, the platform can synthesize a constant locally-administered + MAC address from SoC UID bits that has a good probability of differing + between boards but will be constant on any give board. This helper + will take care of watching for the network devices to appear and + force the MAC to the synthesized one when they do. endif # if NET
This one needs to be either a silent option (only selected by the platforms that want it) or the header file has to provide a static-inline fallback that does nothing, so we don't get a build failure on platforms that need it if the option gets disabled. I'd prefer making it a silent option because then we don't bloat the kernel if someone accidentally enables it on a platform that does not use it.
+static struct mac_la_ap mac_la_ap_list;
The normal way to do this is to have just a list head that the entries get added to: static LIST_HEAD(mac_la_ap_list); That also takes care of the initialization.
+DEFINE_MUTEX(mac_la_ap_mutex); +bool mac_la_ap_started;
These should all be static.
+static int mac_la_ap_init(void)
+{
+ int ret;
+
+ INIT_LIST_HEAD(&mac_la_ap_list.list);
+ mutex_init(&mac_la_ap_mutex);
+ ret = register_netdevice_notifier(&mac_la_ap_netdev_notifier);
+ if (!ret)
+ mac_la_ap_started = 1;
+ else
+ pr_err("mac_la_ap_init: Notifier registration failed\n");
+
+ return ret;
+}The mutex is already initialized, and the list head too if you do the change above. I think it would be simpler to register the notifier from an initcall and drop the mac_la_ap_started variable.
+int mac_la_ap_register_device_macs(const struct mac_la_ap *macs)
+{+} +EXPORT_SYMBOL_GPL(mac_la_ap_register_device_macs);
I'm not sure if there is any point in exporting this function, my feeling is that it would only ever be called from built-in code. If we can call it from a module, we should probably also allow this file to be a loadable module as well. Arnd