b43legacy: Rewrite pwork locking

Implement much easier and more lightweight locking for
the periodic work. This also removes the last big busywait
loop and replaces it by a sleeping loop.

This patch for b43legacy is patterned aftar the same patch
for b43 by Michael Buesch <mb@bu3sch.de>.

Signed-off-by: Larry Finger <larry.finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/b43legacy/main.c b/drivers/net/wireless/b43legacy/main.c
index 069abe5fb8eef6475a0182da1f1aca07e0f41d3f..1daa5aa0ba25ede354099aa8d2440fb06b8d01ac 100644 (file)
--- a/drivers/net/wireless/b43legacy/main.c
+++ b/drivers/net/wireless/b43legacy/main.c
@@ -1797,6 +1797,7 @@ void b43legacy_mac_enable(struct b43legacy_wldev *dev)
 {
        dev->mac_suspended--;
        B43legacy_WARN_ON(dev->mac_suspended < 0);
+       B43legacy_WARN_ON(irqs_disabled());
        if (dev->mac_suspended == 0) {
                b43legacy_write32(dev, B43legacy_MMIO_STATUS_BITFIELD,
                                  b43legacy_read32(dev,
@@ -1808,6 +1809,11 @@ void b43legacy_mac_enable(struct b43legacy_wldev *dev)
                b43legacy_read32(dev, B43legacy_MMIO_STATUS_BITFIELD);
                b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_REASON);
                b43legacy_power_saving_ctl_bits(dev, -1, -1);
+
+               /* Re-enable IRQs. */
+               spin_lock_irq(&dev->wl->irq_lock);
+               b43legacy_interrupt_enable(dev, dev->irq_savedstate);
+               spin_unlock_irq(&dev->wl->irq_lock);
        }
 }
 
@@ -1817,20 +1823,31 @@ void b43legacy_mac_suspend(struct b43legacy_wldev *dev)
        int i;
        u32 tmp;
 
+       might_sleep();
+       B43legacy_WARN_ON(irqs_disabled());
        B43legacy_WARN_ON(dev->mac_suspended < 0);
+
        if (dev->mac_suspended == 0) {
+               /* Mask IRQs before suspending MAC. Otherwise
+                * the MAC stays busy and won't suspend. */
+               spin_lock_irq(&dev->wl->irq_lock);
+               tmp = b43legacy_interrupt_disable(dev, B43legacy_IRQ_ALL);
+               spin_unlock_irq(&dev->wl->irq_lock);
+               b43legacy_synchronize_irq(dev);
+               dev->irq_savedstate = tmp;
+
                b43legacy_power_saving_ctl_bits(dev, -1, 1);
                b43legacy_write32(dev, B43legacy_MMIO_STATUS_BITFIELD,
                                  b43legacy_read32(dev,
                                  B43legacy_MMIO_STATUS_BITFIELD)
                                  & ~B43legacy_SBF_MAC_ENABLED);
                b43legacy_read32(dev, B43legacy_MMIO_GEN_IRQ_REASON);
-               for (i = 10000; i; i--) {
+               for (i = 40; i; i--) {
                        tmp = b43legacy_read32(dev,
                                               B43legacy_MMIO_GEN_IRQ_REASON);
                        if (tmp & B43legacy_IRQ_MAC_SUSPENDED)
                                goto out;
-                       udelay(1);
+                       msleep(1);
                }
                b43legacyerr(dev->wl, "MAC suspend failed\n");
        }
@@ -2145,81 +2162,36 @@ static void do_periodic_work(struct b43legacy_wldev *dev)
        b43legacy_periodic_every15sec(dev);
 }
 
-/* Estimate a "Badness" value based on the periodic work
- * state-machine state. "Badness" is worse (bigger), if the
- * periodic work will take longer.
+/* Periodic work locking policy:
+ *     The whole periodic work handler is protected by
+ *     wl->mutex. If another lock is needed somewhere in the
+ *     pwork callchain, it's aquired in-place, where it's needed.
  */
-static int estimate_periodic_work_badness(unsigned int state)
-{
-       int badness = 0;
-
-       if (state % 8 == 0)     /* every 120 sec */
-               badness += 10;
-       if (state % 4 == 0)     /* every 60 sec */
-               badness += 5;
-       if (state % 2 == 0)     /* every 30 sec */
-               badness += 1;
-
-#define BADNESS_LIMIT  4
-       return badness;
-}
-
 static void b43legacy_periodic_work_handler(struct work_struct *work)
 {
-       struct b43legacy_wldev *dev =
-                            container_of(work, struct b43legacy_wldev,
-                            periodic_work.work);
-       unsigned long flags;
+       struct b43legacy_wldev *dev = container_of(work, struct b43legacy_wldev,
+                                            periodic_work.work);
+       struct b43legacy_wl *wl = dev->wl;
        unsigned long delay;
-       u32 savedirqs = 0;
-       int badness;
 
-       mutex_lock(&dev->wl->mutex);
+       mutex_lock(&wl->mutex);
 
        if (unlikely(b43legacy_status(dev) != B43legacy_STAT_STARTED))
                goto out;
        if (b43legacy_debug(dev, B43legacy_DBG_PWORK_STOP))
                goto out_requeue;
 
-       badness = estimate_periodic_work_badness(dev->periodic_state);
-       if (badness > BADNESS_LIMIT) {
-               spin_lock_irqsave(&dev->wl->irq_lock, flags);
-               /* Suspend TX as we don't want to transmit packets while
-                * we recalibrate the hardware. */
-               b43legacy_tx_suspend(dev);
-               savedirqs = b43legacy_interrupt_disable(dev,
-                                                         B43legacy_IRQ_ALL);
-               /* Periodic work will take a long time, so we want it to
-                * be preemtible and release the spinlock. */
-               spin_unlock_irqrestore(&dev->wl->irq_lock, flags);
-               b43legacy_synchronize_irq(dev);
-
-               do_periodic_work(dev);
-
-               spin_lock_irqsave(&dev->wl->irq_lock, flags);
-               b43legacy_interrupt_enable(dev, savedirqs);
-               b43legacy_tx_resume(dev);
-               mmiowb();
-               spin_unlock_irqrestore(&dev->wl->irq_lock, flags);
-       } else {
-               /* Take the global driver lock. This will lock any operation. */
-               spin_lock_irqsave(&dev->wl->irq_lock, flags);
-
-               do_periodic_work(dev);
+       do_periodic_work(dev);
 
-               mmiowb();
-               spin_unlock_irqrestore(&dev->wl->irq_lock, flags);
-       }
        dev->periodic_state++;
 out_requeue:
        if (b43legacy_debug(dev, B43legacy_DBG_PWORK_FAST))
                delay = msecs_to_jiffies(50);
        else
                delay = round_jiffies_relative(HZ * 15);
-       queue_delayed_work(dev->wl->hw->workqueue,
-                          &dev->periodic_work, delay);
+       queue_delayed_work(wl->hw->workqueue, &dev->periodic_work, delay);
 out:
-       mutex_unlock(&dev->wl->mutex);
+       mutex_unlock(&wl->mutex);
 }
 
 static void b43legacy_periodic_tasks_setup(struct b43legacy_wldev *dev)