batman-adv: add wrapper function to throw uevent in userspace

Using throw_uevent() is now possible to trigger uevent signal that can
be recognised in userspace. Uevents will be triggered through the
/devices/virtual/net/{MESH_IFACE} kobject.

A triggered uevent has three properties:
- type: the event class. Who generates the event (only 'gw' is currently
  defined). Corresponds to the BATTYPE uevent variable.
- action: the associated action with the event ('add'/'change'/'del' are
  currently defined). Corresponds to the BATACTION uevent variable.
- data: any useful data for the userspace. Corresponds to the BATDATA
  uevent variable.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Sven Eckelmann <sven@narfation.org>

1 files changed, 71 insertions, 0 deletions

diff --git a/net/batman-adv/bat_sysfs.c b/net/batman-adv/bat_sysfs.c
index 63738ec10511..cd15deba60a1 100644
--- a/net/batman-adv/bat_sysfs.c
+++ b/net/batman-adv/bat_sysfs.c
@@ -40,6 +40,20 @@ static struct bat_priv *kobj_to_batpriv(struct kobject *obj)
         return netdev_priv(net_dev);
 }
 
+#define UEV_TYPE_VAR    "BATTYPE="
+#define UEV_ACTION_VAR  "BATACTION="
+#define UEV_DATA_VAR    "BATDATA="
+
+static char *uev_action_str[] = {
+        "add",
+        "del",
+        "change"
+};
+
+static char *uev_type_str[] = {
+        "gw"
+};
+
 /* Use this, if you have customized show and store functions */
 #define BAT_ATTR(_name, _mode, _show, _store)   \
 struct bat_attribute bat_attr_##_name = {       \
@@ -601,3 +615,60 @@ void sysfs_del_hardif(struct kobject **hardif_obj)
         kobject_put(*hardif_obj);
         *hardif_obj = NULL;
 }
+
+int throw_uevent(struct bat_priv *bat_priv, enum uev_type type,
+                 enum uev_action action, const char *data)
+{
+        int ret = -1;
+        struct hard_iface *primary_if = NULL;
+        struct kobject *bat_kobj;
+        char *uevent_env[4] = { NULL, NULL, NULL, NULL };
+
+        primary_if = primary_if_get_selected(bat_priv);
+        if (!primary_if)
+                goto out;
+
+        bat_kobj = &primary_if->soft_iface->dev.kobj;
+
+        uevent_env[0] = kmalloc(strlen(UEV_TYPE_VAR) +
+                                strlen(uev_type_str[type]) + 1,
+                                GFP_ATOMIC);
+        if (!uevent_env[0])
+                goto out;
+
+        sprintf(uevent_env[0], "%s%s", UEV_TYPE_VAR, uev_type_str[type]);
+
+        uevent_env[1] = kmalloc(strlen(UEV_ACTION_VAR) +
+                                strlen(uev_action_str[action]) + 1,
+                                GFP_ATOMIC);
+        if (!uevent_env[1])
+                goto out;
+
+        sprintf(uevent_env[1], "%s%s", UEV_ACTION_VAR, uev_action_str[action]);
+
+        /* If the event is DEL, ignore the data field */
+        if (action != UEV_DEL) {
+                uevent_env[2] = kmalloc(strlen(UEV_DATA_VAR) +
+                                        strlen(data) + 1, GFP_ATOMIC);
+                if (!uevent_env[2])
+                        goto out;
+
+                sprintf(uevent_env[2], "%s%s", UEV_DATA_VAR, data);
+        }
+
+        ret = kobject_uevent_env(bat_kobj, KOBJ_CHANGE, uevent_env);
+out:
+        kfree(uevent_env[0]);
+        kfree(uevent_env[1]);
+        kfree(uevent_env[2]);
+
+        if (primary_if)
+                hardif_free_ref(primary_if);
+
+        if (ret)
+                bat_dbg(DBG_BATMAN, bat_priv, "Impossible to send "
+                        "uevent for (%s,%s,%s) event (err: %d)\n",
+                        uev_type_str[type], uev_action_str[action],
+                        (action == UEV_DEL ? "NULL" : data), ret);
+        return ret;
+}