Re: [RFC 3/4] wwan: add interface creation support

From: Johannes Berg <redacted>

Add support to create (and destroy) interfaces via a new
rtnetlink kind "wwan". The responsible driver has to use
the new wwan_register_ops() to make this possible.

Signed-off-by: Johannes Berg <redacted>
---
 drivers/net/wwan/wwan_core.c | 219 ++++++++++++++++++++++++++++++++++-
 include/linux/wwan.h         |  36 ++++++
 include/uapi/linux/wwan.h    |  17 +++
 3 files changed, 267 insertions(+), 5 deletions(-)
 create mode 100644 include/uapi/linux/wwan.h

diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index cff04e532c1e..b1ad78f386bc 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c

@@ -13,6 +13,8 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/wwan.h>
+#include <net/rtnetlink.h>
+#include <uapi/linux/wwan.h>

 #define WWAN_MAX_MINORS 256 /* 256 minors allowed with register_chrdev() */

@@ -524,24 +526,231 @@ static const struct file_operations wwan_port_fops = {
        .llseek = noop_llseek,
 };

+struct wwan_dev_reg {
+       struct list_head list;
+       struct device *dev;
+       const struct wwan_ops *ops;
+       void *ctxt;
+};
+
+static DEFINE_MUTEX(wwan_mtx);
+static LIST_HEAD(wwan_devs);
+
+int wwan_register_ops(struct device *parent, const struct wwan_ops *ops,
+                     void *ctxt)
+{
+       struct wwan_dev_reg *reg;
+       int ret;
+
+       if (WARN_ON(!parent || !ops))
+               return -EINVAL;
+
+       mutex_lock(&wwan_mtx);
+       list_for_each_entry(reg, &wwan_devs, list) {
+               if (WARN_ON(reg->dev == parent)) {
+                       ret = -EBUSY;
+                       goto out;
+               }
+       }