rt2x00: Fix race conditions in flag handling

Some of the flags should be accessed atomically to
prevent race conditions. The flags that are most important
are those that can change often and indicate the actual
state of the device, queue or queue entry.

The big flag rename was done to move all state flags to
the same naming type as the other rt2x00dev flags and
made sure all places where the flags were used were changed. ;)

Thanks to Stephen for most of the queue flags updates,
which fixes some of the most obvious consequences of the
race conditions. Among those the notorious:

rt2x00queue_write_tx_frame: Error - Arrived at non-free entry in the non-full queue 0.
rt2x00queue_write_tx_frame: Error - Arrived at non-free entry in the non-full queue 0.
rt2x00queue_write_tx_frame: Error - Arrived at non-free entry in the non-full queue 0.

Signed-off-by: Stephen Blackheath <tramp.enshrine.stephen@blacksapphire.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 30 insertions, 28 deletions

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 328ff8bc4c1..330ab77902f 100644
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -34,7 +34,7 @@
  */
 void rt2x00lib_reset_link_tuner(struct rt2x00_dev *rt2x00dev)
 {
-	if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags))
+	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;
 
 	/*
@@ -94,8 +94,8 @@ int rt2x00lib_enable_radio(struct rt2x00_dev *rt2x00dev)
 	 * Don't enable the radio twice.
 	 * And check if the hardware button has been disabled.
 	 */
-	if (test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags) ||
-	    test_bit(DEVICE_DISABLED_RADIO_HW, &rt2x00dev->flags))
+	if (test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags) ||
+	    test_bit(DEVICE_STATE_DISABLED_RADIO_HW, &rt2x00dev->flags))
 		return 0;
 
 	/*
@@ -117,7 +117,7 @@ int rt2x00lib_enable_radio(struct rt2x00_dev *rt2x00dev)
 	rt2x00leds_led_radio(rt2x00dev, true);
 	rt2x00led_led_activity(rt2x00dev, true);
 
-	__set_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags);
 
 	/*
 	 * Enable RX.
@@ -134,7 +134,7 @@ int rt2x00lib_enable_radio(struct rt2x00_dev *rt2x00dev)
 
 void rt2x00lib_disable_radio(struct rt2x00_dev *rt2x00dev)
 {
-	if (!__test_and_clear_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags))
+	if (!test_and_clear_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;
 
 	/*
@@ -354,7 +354,7 @@ static void rt2x00lib_link_tuner(struct work_struct *work)
 	 * When the radio is shutting down we should
 	 * immediately cease all link tuning.
 	 */
-	if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags))
+	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;
 
 	/*
@@ -431,7 +431,7 @@ static void rt2x00lib_intf_scheduled_iter(void *data, u8 *mac,
 	 * note that in the spinlock protected area above the delayed_flags
 	 * have been cleared correctly.
 	 */
-	if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags))
+	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;
 
 	if (delayed_flags & DELAYED_UPDATE_BEACON)
@@ -484,7 +484,7 @@ static void rt2x00lib_beacondone_iter(void *data, u8 *mac,
 
 void rt2x00lib_beacondone(struct rt2x00_dev *rt2x00dev)
 {
-	if (!test_bit(DEVICE_ENABLED_RADIO, &rt2x00dev->flags))
+	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
 		return;
 
 	ieee80211_iterate_active_interfaces_atomic(rt2x00dev->hw,
@@ -572,7 +572,7 @@ void rt2x00lib_txdone(struct queue_entry *entry,
 
 	rt2x00dev->ops->lib->init_txentry(rt2x00dev, entry);
 
-	__clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags);
+	clear_bit(ENTRY_OWNER_DEVICE_DATA, &entry->flags);
 	rt2x00queue_index_inc(entry->queue, Q_INDEX_DONE);
 
 	/*
@@ -888,7 +888,7 @@ static int rt2x00lib_probe_hw_modes(struct rt2x00_dev *rt2x00dev,
 
 static void rt2x00lib_remove_hw(struct rt2x00_dev *rt2x00dev)
 {
-	if (test_bit(DEVICE_REGISTERED_HW, &rt2x00dev->flags))
+	if (test_bit(DEVICE_STATE_REGISTERED_HW, &rt2x00dev->flags))
 		ieee80211_unregister_hw(rt2x00dev->hw);
 
 	if (likely(rt2x00dev->hw->wiphy->bands[IEEE80211_BAND_2GHZ])) {
@@ -906,6 +906,9 @@ static int rt2x00lib_probe_hw(struct rt2x00_dev *rt2x00dev)
 	struct hw_mode_spec *spec = &rt2x00dev->spec;
 	int status;
 
+	if (test_bit(DEVICE_STATE_REGISTERED_HW, &rt2x00dev->flags))
+		return 0;
+
 	/*
 	 * Initialize HW modes.
 	 */
@@ -927,7 +930,7 @@ static int rt2x00lib_probe_hw(struct rt2x00_dev *rt2x00dev)
 		return status;
 	}
 
-	__set_bit(DEVICE_REGISTERED_HW, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_REGISTERED_HW, &rt2x00dev->flags);
 
 	return 0;
 }
@@ -937,7 +940,7 @@ static int rt2x00lib_probe_hw(struct rt2x00_dev *rt2x00dev)
  */
 static void rt2x00lib_uninitialize(struct rt2x00_dev *rt2x00dev)
 {
-	if (!__test_and_clear_bit(DEVICE_INITIALIZED, &rt2x00dev->flags))
+	if (!test_and_clear_bit(DEVICE_STATE_INITIALIZED, &rt2x00dev->flags))
 		return;
 
 	/*
@@ -960,7 +963,7 @@ static int rt2x00lib_initialize(struct rt2x00_dev *rt2x00dev)
 {
 	int status;
 
-	if (test_bit(DEVICE_INITIALIZED, &rt2x00dev->flags))
+	if (test_bit(DEVICE_STATE_INITIALIZED, &rt2x00dev->flags))
 		return 0;
 
 	/*
@@ -979,7 +982,7 @@ static int rt2x00lib_initialize(struct rt2x00_dev *rt2x00dev)
 		return status;
 	}
 
-	__set_bit(DEVICE_INITIALIZED, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_INITIALIZED, &rt2x00dev->flags);
 
 	/*
 	 * Register the extra components.
@@ -993,7 +996,7 @@ int rt2x00lib_start(struct rt2x00_dev *rt2x00dev)
 {
 	int retval;
 
-	if (test_bit(DEVICE_STARTED, &rt2x00dev->flags))
+	if (test_bit(DEVICE_STATE_STARTED, &rt2x00dev->flags))
 		return 0;
 
 	/*
@@ -1024,15 +1027,15 @@ int rt2x00lib_start(struct rt2x00_dev *rt2x00dev)
 	rt2x00dev->intf_sta_count = 0;
 	rt2x00dev->intf_associated = 0;
 
-	__set_bit(DEVICE_STARTED, &rt2x00dev->flags);
-	__set_bit(DEVICE_DIRTY_CONFIG, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_STARTED, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_DIRTY_CONFIG, &rt2x00dev->flags);
 
 	return 0;
 }
 
 void rt2x00lib_stop(struct rt2x00_dev *rt2x00dev)
 {
-	if (!test_bit(DEVICE_STARTED, &rt2x00dev->flags))
+	if (!test_and_clear_bit(DEVICE_STATE_STARTED, &rt2x00dev->flags))
 		return;
 
 	/*
@@ -1044,8 +1047,6 @@ void rt2x00lib_stop(struct rt2x00_dev *rt2x00dev)
 	rt2x00dev->intf_ap_count = 0;
 	rt2x00dev->intf_sta_count = 0;
 	rt2x00dev->intf_associated = 0;
-
-	__clear_bit(DEVICE_STARTED, &rt2x00dev->flags);
 }
 
 /*
@@ -1100,7 +1101,7 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 	rt2x00rfkill_allocate(rt2x00dev);
 	rt2x00debug_register(rt2x00dev);
 
-	__set_bit(DEVICE_PRESENT, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 
 	return 0;
 
@@ -1113,7 +1114,7 @@ EXPORT_SYMBOL_GPL(rt2x00lib_probe_dev);
 
 void rt2x00lib_remove_dev(struct rt2x00_dev *rt2x00dev)
 {
-	__clear_bit(DEVICE_PRESENT, &rt2x00dev->flags);
+	clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 
 	/*
 	 * Disable radio.
@@ -1158,14 +1159,15 @@ int rt2x00lib_suspend(struct rt2x00_dev *rt2x00dev, pm_message_t state)
 	int retval;
 
 	NOTICE(rt2x00dev, "Going to sleep.\n");
-	__clear_bit(DEVICE_PRESENT, &rt2x00dev->flags);
 
 	/*
 	 * Only continue if mac80211 has open interfaces.
 	 */
-	if (!test_bit(DEVICE_STARTED, &rt2x00dev->flags))
+	if (!test_and_clear_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags) ||
+	    !test_bit(DEVICE_STATE_STARTED, &rt2x00dev->flags))
 		goto exit;
-	__set_bit(DEVICE_STARTED_SUSPEND, &rt2x00dev->flags);
+
+	set_bit(DEVICE_STATE_STARTED_SUSPEND, &rt2x00dev->flags);
 
 	/*
 	 * Disable radio.
@@ -1237,7 +1239,7 @@ int rt2x00lib_resume(struct rt2x00_dev *rt2x00dev)
 	/*
 	 * Only continue if mac80211 had open interfaces.
 	 */
-	if (!__test_and_clear_bit(DEVICE_STARTED_SUSPEND, &rt2x00dev->flags))
+	if (!test_and_clear_bit(DEVICE_STATE_STARTED_SUSPEND, &rt2x00dev->flags))
 		return 0;
 
 	/*
@@ -1264,7 +1266,7 @@ int rt2x00lib_resume(struct rt2x00_dev *rt2x00dev)
 	/*
 	 * We are ready again to receive requests from mac80211.
 	 */
-	__set_bit(DEVICE_PRESENT, &rt2x00dev->flags);
+	set_bit(DEVICE_STATE_PRESENT, &rt2x00dev->flags);
 
 	/*
 	 * It is possible that during that mac80211 has attempted
@@ -1284,7 +1286,7 @@ int rt2x00lib_resume(struct rt2x00_dev *rt2x00dev)
 	return 0;
 
 exit:
-	rt2x00lib_disable_radio(rt2x00dev);
+	rt2x00lib_stop(rt2x00dev);
 	rt2x00lib_uninitialize(rt2x00dev);
 	rt2x00debug_deregister(rt2x00dev);