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authorGrant Erickson <marathon96@gmail.com>2013-04-11 07:28:11 (GMT)
committerPatrik Flykt <patrik.flykt@linux.intel.com>2013-04-11 23:15:55 (GMT)
commit74798430e79654c8ee1391f4ac5b21faca56e0a4 (patch)
tree00d7c98ead5221ec10d91d5f3f4dbd2ce2fe4047 /plugins
parentc2ed55115bb97ffd4770f2d49667c515f39b34e7 (diff)
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wifi: avoid device double release on disable
Per MEEGO-25999 <https://bugs.meego.com/show_bug.cgi?id=25999>, there exists a race between scan_callback and wifi_disable such that a care- fully-timed deassertion of the technology Powered property between throw_wifi_scan and scan_callback will lead to a device reference count underflow. A second Powered property false -> true -> false transition will then deallocate the device and Wi-Fi will no longer function until connman or the system is restarted. This patch addresses that race by tracking and observing the disabling state such that scan_callback ad wifi_disable can effectively negotiate which has performed the device release, thereby avoiding the double release and resulting underflow.
Diffstat (limited to 'plugins')
-rw-r--r--plugins/wifi.c40
1 files changed, 38 insertions, 2 deletions
diff --git a/plugins/wifi.c b/plugins/wifi.c
index a0cb966..f862703 100644
--- a/plugins/wifi.c
+++ b/plugins/wifi.c
@@ -93,6 +93,7 @@ struct wifi_data {
GSList *networks;
GSupplicantInterface *interface;
GSupplicantState state;
+ connman_bool_t disabling;
connman_bool_t connected;
connman_bool_t disconnecting;
connman_bool_t tethering;
@@ -171,6 +172,7 @@ static int wifi_probe(struct connman_device *device)
if (wifi == NULL)
return -ENOMEM;
+ wifi->disabling = FALSE;
wifi->connected = FALSE;
wifi->disconnecting = FALSE;
wifi->tethering = FALSE;
@@ -527,7 +529,14 @@ static void scan_callback(int result, GSupplicantInterface *interface,
if (result != -ENOLINK)
start_autoscan(device);
- connman_device_unref(device);
+ /*
+ * If we are here then we were scanning; however, if we are also
+ * mid-flight disabling the interface, then wifi_disable has
+ * already unreferenced the device and we needn't do it here.
+ */
+
+ if (wifi->disabling != TRUE)
+ connman_device_unref(device);
}
static void scan_callback_hidden(int result,
@@ -724,6 +733,27 @@ static void interface_create_callback(int result,
}
}
+/*
+ * The sole function of this callback is to avoid a race between scan completion
+ * and wifi_disable that can otherwise cause a reference count underflow if the
+ * disabling state is not tracked and observed.
+ */
+static void interface_remove_callback(int result,
+ GSupplicantInterface *interface,
+ void *user_data)
+{
+ struct wifi_data *wifi = user_data;
+
+ DBG("result %d ifname %s, wifi %p", result,
+ g_supplicant_interface_get_ifname(interface),
+ wifi);
+
+ if (result < 0 || wifi == NULL)
+ return;
+
+ wifi->disabling = FALSE;
+}
+
static int wifi_enable(struct connman_device *device)
{
struct wifi_data *wifi = connman_device_get_data(device);
@@ -742,6 +772,8 @@ static int wifi_enable(struct connman_device *device)
if (ret < 0)
return ret;
+ wifi->disabling = FALSE;
+
return -EINPROGRESS;
}
@@ -771,10 +803,14 @@ static int wifi_disable(struct connman_device *device)
remove_networks(device, wifi);
- ret = g_supplicant_interface_remove(wifi->interface, NULL, NULL);
+ ret = g_supplicant_interface_remove(wifi->interface,
+ interface_remove_callback,
+ wifi);
if (ret < 0)
return ret;
+ wifi->disabling = TRUE;
+
return -EINPROGRESS;
}