[B43]: Rewrite pwork locking policy.

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.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 32 insertions, 56 deletions

diff --git a/drivers/net/wireless/b43/main.c b/drivers/net/wireless/b43/main.c
index a603a154d496..6c80f2e2f4ee 100644
--- a/drivers/net/wireless/b43/main.c
+++ b/drivers/net/wireless/b43/main.c
@@ -1976,6 +1976,7 @@ void b43_mac_enable(struct b43_wldev *dev)
 {
         dev->mac_suspended--;
         B43_WARN_ON(dev->mac_suspended < 0);
+        B43_WARN_ON(irqs_disabled());
         if (dev->mac_suspended == 0) {
                 b43_write32(dev, B43_MMIO_MACCTL,
                             b43_read32(dev, B43_MMIO_MACCTL)
@@ -1986,6 +1987,11 @@ void b43_mac_enable(struct b43_wldev *dev)
                 b43_read32(dev, B43_MMIO_MACCTL);
                 b43_read32(dev, B43_MMIO_GEN_IRQ_REASON);
                 b43_power_saving_ctl_bits(dev, 0);
+
+                /* Re-enable IRQs. */
+                spin_lock_irq(&dev->wl->irq_lock);
+                b43_interrupt_enable(dev, dev->irq_savedstate);
+                spin_unlock_irq(&dev->wl->irq_lock);
         }
 }
 
@@ -1995,23 +2001,34 @@ void b43_mac_suspend(struct b43_wldev *dev)
         int i;
         u32 tmp;
 
+        might_sleep();
+        B43_WARN_ON(irqs_disabled());
         B43_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 = b43_interrupt_disable(dev, B43_IRQ_ALL);
+                spin_unlock_irq(&dev->wl->irq_lock);
+                b43_synchronize_irq(dev);
+                dev->irq_savedstate = tmp;
+
                 b43_power_saving_ctl_bits(dev, B43_PS_AWAKE);
                 b43_write32(dev, B43_MMIO_MACCTL,
                             b43_read32(dev, B43_MMIO_MACCTL)
                             & ~B43_MACCTL_ENABLED);
                 /* force pci to flush the write */
                 b43_read32(dev, B43_MMIO_MACCTL);
-                for (i = 10000; i; i--) {
+                for (i = 40; i; i--) {
                         tmp = b43_read32(dev, B43_MMIO_GEN_IRQ_REASON);
                         if (tmp & B43_IRQ_MAC_SUSPENDED)
                                 goto out;
-                        udelay(1);
+                        msleep(1);
                 }
                 b43err(dev->wl, "MAC suspend failed\n");
         }
-      out:
+out:
         dev->mac_suspended++;
 }
 
@@ -2349,77 +2366,36 @@ static void do_periodic_work(struct b43_wldev *dev)
         b43_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 b43_periodic_work_handler(struct work_struct *work)
 {
-        struct b43_wldev *dev =
-            container_of(work, struct b43_wldev, periodic_work.work);
-        unsigned long flags, delay;
-        u32 savedirqs = 0;
-        int badness;
+        struct b43_wldev *dev = container_of(work, struct b43_wldev,
+                                             periodic_work.work);
+        struct b43_wl *wl = dev->wl;
+        unsigned long delay;
 
-        mutex_lock(&dev->wl->mutex);
+        mutex_lock(&wl->mutex);
 
         if (unlikely(b43_status(dev) != B43_STAT_STARTED))
                 goto out;
         if (b43_debug(dev, B43_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. */
-                b43_tx_suspend(dev);
-                savedirqs = b43_interrupt_disable(dev, B43_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);
-                b43_synchronize_irq(dev);
-
-                do_periodic_work(dev);
-
-                spin_lock_irqsave(&dev->wl->irq_lock, flags);
-                b43_interrupt_enable(dev, savedirqs);
-                b43_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 (b43_debug(dev, B43_DBG_PWORK_FAST))
                 delay = msecs_to_jiffies(50);
         else
                 delay = round_jiffies(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 b43_periodic_tasks_setup(struct b43_wldev *dev)