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>

1 files changed, 30 insertions, 58 deletions

diff --git a/drivers/net/wireless/b43legacy/main.c b/drivers/net/wireless/b43legacy/main.c
index 069abe5fb8e..1daa5aa0ba2 100644
--- 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)