b43: Fix some TX/RX locking issues

This fixes some TX/RX related locking issues.
With this patch applied, some of the PHY transmission errors are fixed.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/b43/b43.h

@@ -691,6 +691,10 @@ struct b43_wl {
 
 	struct mutex mutex;
 	spinlock_t irq_lock;
+	/* R/W lock for data transmission.
+	 * Transmissions on 2+ queues can run concurrently, but somebody else
+	 * might sync with TX by write_lock_irqsave()'ing. */
+	rwlock_t tx_lock;
 	/* Lock for LEDs access. */
 	spinlock_t leds_lock;
 	/* Lock for SHM access. */

drivers/net/wireless/b43/main.c

@@ -729,6 +729,7 @@ static void b43_synchronize_irq(struct b43_wldev *dev)
  */
 void b43_dummy_transmission(struct b43_wldev *dev)
 {
+	struct b43_wl *wl = dev->wl;
 	struct b43_phy *phy = &dev->phy;
 	unsigned int i, max_loop;
 	u16 value;
@@ -755,6 +756,9 @@ void b43_dummy_transmission(struct b43_wldev *dev)
 		return;
 	}
 
+	spin_lock_irq(&wl->irq_lock);
+	write_lock(&wl->tx_lock);
+
 	for (i = 0; i < 5; i++)
 		b43_ram_write(dev, i * 4, buffer[i]);
 
@@ -795,6 +799,9 @@ void b43_dummy_transmission(struct b43_wldev *dev)
 	}
 	if (phy->radio_ver == 0x2050 && phy->radio_rev <= 0x5)
 		b43_radio_write16(dev, 0x0051, 0x0037);
+
+	write_unlock(&wl->tx_lock);
+	spin_unlock_irq(&wl->irq_lock);
 }
 
 static void key_write(struct b43_wldev *dev,
@@ -2840,24 +2847,31 @@ static int b43_op_tx(struct ieee80211_hw *hw,
 {
 	struct b43_wl *wl = hw_to_b43_wl(hw);
 	struct b43_wldev *dev = wl->current_dev;
-	int err = -ENODEV;
+	unsigned long flags;
+	int err;
 
 	if (unlikely(skb->len < 2 + 2 + 6)) {
 		/* Too short, this can't be a valid frame. */
-		return -EINVAL;
+		dev_kfree_skb_any(skb);
+		return NETDEV_TX_OK;
 	}
 	B43_WARN_ON(skb_shinfo(skb)->nr_frags);
-
 	if (unlikely(!dev))
-		goto out;
-	if (unlikely(b43_status(dev) < B43_STAT_STARTED))
-		goto out;
-	/* TX is done without a global lock. */
+		return NETDEV_TX_BUSY;
+
+	/* Transmissions on seperate queues can run concurrently. */
+	read_lock_irqsave(&wl->tx_lock, flags);
+
+	err = -ENODEV;
+	if (likely(b43_status(dev) >= B43_STAT_STARTED)) {
 		if (b43_using_pio_transfers(dev))
 			err = b43_pio_tx(dev, skb, ctl);
 		else
 			err = b43_dma_tx(dev, skb, ctl);
-out:
+	}
+
+	read_unlock_irqrestore(&wl->tx_lock, flags);
+
 	if (unlikely(err))
 		return NETDEV_TX_BUSY;
 	return NETDEV_TX_OK;
@@ -3476,7 +3490,9 @@ static void b43_wireless_core_stop(struct b43_wldev *dev)
 	spin_unlock_irqrestore(&wl->irq_lock, flags);
 	b43_synchronize_irq(dev);
 
+	write_lock_irqsave(&wl->tx_lock, flags);
 	b43_set_status(dev, B43_STAT_INITIALIZED);
+	write_unlock_irqrestore(&wl->tx_lock, flags);
 
 	b43_pio_stop(dev);
 	mutex_unlock(&wl->mutex);
@@ -3485,8 +3501,6 @@ static void b43_wireless_core_stop(struct b43_wldev *dev)
 	cancel_delayed_work_sync(&dev->periodic_work);
 	mutex_lock(&wl->mutex);
 
-	ieee80211_stop_queues(wl->hw);	//FIXME this could cause a deadlock, as mac80211 seems buggy.
-
 	b43_mac_suspend(dev);
 	free_irq(dev->dev->irq, dev);
 	b43dbg(wl, "Wireless interface stopped\n");
@@ -4498,6 +4512,7 @@ static int b43_wireless_init(struct ssb_device *dev)
 	memset(wl, 0, sizeof(*wl));
 	wl->hw = hw;
 	spin_lock_init(&wl->irq_lock);
+	rwlock_init(&wl->tx_lock);
 	spin_lock_init(&wl->leds_lock);
 	spin_lock_init(&wl->shm_lock);
 	mutex_init(&wl->mutex);