[PATCH] b43: Fix some TX/RX locking issues

[Michael Buesch <mb@bu3sch.de>]

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>

---

John, this is for 2.6.26.


Index: wireless-testing/drivers/net/wireless/b43/b43.h
===================================================================
--- wireless-testing.orig/drivers/net/wireless/b43/b43.h	2008-04-24 19:42:55.000000000 +0200
+++ wireless-testing/drivers/net/wireless/b43/b43.h	2008-04-25 19:28:42.000000000 +0200
@@ -688,12 +688,16 @@ struct b43_wl {
 	struct b43_wldev *current_dev;
 	/* Pointer to the ieee80211 hardware data structure */
 	struct ieee80211_hw *hw;
 
 	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. */
 	spinlock_t shm_lock;
 
 	/* We can only have one operating interface (802.11 core)
Index: wireless-testing/drivers/net/wireless/b43/main.c
===================================================================
--- wireless-testing.orig/drivers/net/wireless/b43/main.c	2008-04-24 19:42:55.000000000 +0200
+++ wireless-testing/drivers/net/wireless/b43/main.c	2008-04-25 18:47:08.000000000 +0200
@@ -726,12 +726,13 @@ static void b43_synchronize_irq(struct b
 
 /* DummyTransmission function, as documented on
  * http://bcm-specs.sipsolutions.net/DummyTransmission
  */
 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;
 	u32 buffer[5] = {
 		0x00000000,
 		0x00D40000,
@@ -752,12 +753,15 @@ void b43_dummy_transmission(struct b43_w
 		break;
 	default:
 		B43_WARN_ON(1);
 		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]);
 
 	/* Commit writes */
 	b43_read32(dev, B43_MMIO_MACCTL);
 
@@ -792,12 +796,15 @@ void b43_dummy_transmission(struct b43_w
 		if (!(value & 0x0100))
 			break;
 		udelay(10);
 	}
 	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,
 		      u8 index, u8 algorithm, const u8 * key)
 {
 	unsigned int i;
@@ -2821,30 +2828,37 @@ static int b43_rng_init(struct b43_wl *w
 static int b43_op_tx(struct ieee80211_hw *hw,
 		     struct sk_buff *skb,
 		     struct ieee80211_tx_control *ctl)
 {
 	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. */
-	if (b43_using_pio_transfers(dev))
-		err = b43_pio_tx(dev, skb, ctl);
-	else
-		err = b43_dma_tx(dev, skb, ctl);
-out:
+		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);
+	}
+
+	read_unlock_irqrestore(&wl->tx_lock, flags);
+
 	if (unlikely(err))
 		return NETDEV_TX_BUSY;
 	return NETDEV_TX_OK;
 }
 
 /* Locking: wl->irq_lock */
@@ -3457,23 +3471,23 @@ static void b43_wireless_core_stop(struc
 	spin_lock_irqsave(&wl->irq_lock, flags);
 	dev->irq_savedstate = b43_interrupt_disable(dev, B43_IRQ_ALL);
 	b43_read32(dev, B43_MMIO_GEN_IRQ_MASK);	/* flush */
 	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);
 	/* Must unlock as it would otherwise deadlock. No races here.
 	 * Cancel the possibly running self-rearming periodic work. */
 	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");
 }
 
 /* Locking: wl->mutex */
@@ -4471,12 +4485,13 @@ static int b43_wireless_init(struct ssb_
 
 	/* Get and initialize struct b43_wl */
 	wl = hw_to_b43_wl(hw);
 	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);
 	INIT_LIST_HEAD(&wl->devlist);
 	INIT_WORK(&wl->qos_update_work, b43_qos_update_work);
 	INIT_WORK(&wl->beacon_update_trigger, b43_beacon_update_trigger_work);