[PATCH] bcm43xx: redesign locking

Redesign the bcm43xx locking.
This is pre-work to get a preemptible periodic work handler.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/bcm43xx/bcm43xx.h

@@ -636,6 +636,17 @@ struct bcm43xx_key {
 	u8 algorithm;
 };
 
+/* Driver initialization status. */
+enum {
+	BCM43xx_STAT_UNINIT,		/* Uninitialized. */
+	BCM43xx_STAT_INITIALIZING,	/* init_board() in progress. */
+	BCM43xx_STAT_INITIALIZED,	/* Fully operational. */
+	BCM43xx_STAT_SHUTTINGDOWN,	/* free_board() in progress. */
+	BCM43xx_STAT_RESTARTING,	/* controller_restart() called. */
+};
+#define bcm43xx_status(bcm)		atomic_read(&(bcm)->init_status)
+#define bcm43xx_set_status(bcm, stat)	atomic_set(&(bcm)->init_status, (stat))
+
 struct bcm43xx_private {
 	struct ieee80211_device *ieee;
 	struct ieee80211softmac_device *softmac;
@@ -646,18 +657,17 @@ struct bcm43xx_private {
 
 	void __iomem *mmio_addr;
 
-	/* Do not use the lock directly. Use the bcm43xx_lock* helper
-	 * functions, to be MMIO-safe. */
-	spinlock_t _lock;
+	/* Locking, see "theory of locking" text below. */
+	spinlock_t irq_lock;
+	struct mutex mutex;
+
+	/* Driver initialization status BCM43xx_STAT_*** */
+	atomic_t init_status;
 
-	/* Driver status flags. */
-	u32 initialized:1,		/* init_board() succeed */
-	    was_initialized:1,		/* for PCI suspend/resume. */
-	    shutting_down:1,		/* free_board() in progress */
+	u16 was_initialized:1,		/* for PCI suspend/resume. */
 	    __using_pio:1,		/* Internal, use bcm43xx_using_pio(). */
 	    bad_frames_preempt:1,	/* Use "Bad Frames Preemption" (default off) */
 	    reg124_set_0x4:1,		/* Some variable to keep track of IRQ stuff. */
-	    powersaving:1,		/* TRUE if we are in PowerSaving mode. FALSE otherwise. */
 	    short_preamble:1,		/* TRUE, if short preamble is enabled. */
 	    firmware_norelease:1;	/* Do not release the firmware. Used on suspend. */
 
@@ -721,7 +731,7 @@ struct bcm43xx_private {
 	struct tasklet_struct isr_tasklet;
 
 	/* Periodic tasks */
-	struct timer_list periodic_tasks;
+	struct work_struct periodic_work;
 	unsigned int periodic_state;
 
 	struct work_struct restart_work;
@@ -746,21 +756,55 @@ struct bcm43xx_private {
 #endif
 };
 
-/* bcm43xx_(un)lock() protect struct bcm43xx_private.
- * Note that _NO_ MMIO writes are allowed. If you want to
- * write to the device through MMIO in the critical section, use
- * the *_mmio lock functions.
- * MMIO read-access is allowed, though.
- */
-#define bcm43xx_lock(bcm, flags)	spin_lock_irqsave(&(bcm)->_lock, flags)
-#define bcm43xx_unlock(bcm, flags)	spin_unlock_irqrestore(&(bcm)->_lock, flags)
-/* bcm43xx_(un)lock_mmio() protect struct bcm43xx_private and MMIO.
- * MMIO write-access to the device is allowed.
- * All MMIO writes are flushed on unlock, so it is guaranteed to not
- * interfere with other threads writing MMIO registers.
+
+/*    *** THEORY OF LOCKING ***
+ *
+ * We have two different locks in the bcm43xx driver.
+ * => bcm->mutex:    General sleeping mutex. Protects struct bcm43xx_private
+ *                   and the device registers.
+ * => bcm->irq_lock: IRQ spinlock. Protects against IRQ handler concurrency.
+ *
+ * We have three types of helper function pairs to utilize these locks.
+ *     (Always use the helper functions.)
+ * 1) bcm43xx_{un}lock_noirq():
+ *     Takes bcm->mutex. Does _not_ protect against IRQ concurrency,
+ *     so it is almost always unsafe, if device IRQs are enabled.
+ *     So only use this, if device IRQs are masked.
+ *     Locking may sleep.
+ *     You can sleep within the critical section.
+ * 2) bcm43xx_{un}lock_irqonly():
+ *     Takes bcm->irq_lock. Does _not_ protect against
+ *     bcm43xx_lock_noirq() critical sections.
+ *     Does only protect against the IRQ handler path and other
+ *     irqonly() critical sections.
+ *     Locking does not sleep.
+ *     You must not sleep within the critical section.
+ * 3) bcm43xx_{un}lock_irqsafe():
+ *     This is the cummulative lock and takes both, mutex and irq_lock.
+ *     Protects against noirq() and irqonly() critical sections (and
+ *     the IRQ handler path).
+ *     Locking may sleep.
+ *     You must not sleep within the critical section.
  */
-#define bcm43xx_lock_mmio(bcm, flags)	bcm43xx_lock(bcm, flags)
-#define bcm43xx_unlock_mmio(bcm, flags)	do { mmiowb(); bcm43xx_unlock(bcm, flags); } while (0)
+
+/* Lock type 1 */
+#define bcm43xx_lock_noirq(bcm)		mutex_lock(&(bcm)->mutex)
+#define bcm43xx_unlock_noirq(bcm)	mutex_unlock(&(bcm)->mutex)
+/* Lock type 2 */
+#define bcm43xx_lock_irqonly(bcm, flags)	\
+	spin_lock_irqsave(&(bcm)->irq_lock, flags)
+#define bcm43xx_unlock_irqonly(bcm, flags)	\
+	spin_unlock_irqrestore(&(bcm)->irq_lock, flags)
+/* Lock type 3 */
+#define bcm43xx_lock_irqsafe(bcm, flags) do {	\
+	bcm43xx_lock_noirq(bcm);		\
+	bcm43xx_lock_irqonly(bcm, flags);	\
+		} while (0)
+#define bcm43xx_unlock_irqsafe(bcm, flags) do {	\
+	bcm43xx_unlock_irqonly(bcm, flags);	\
+	bcm43xx_unlock_noirq(bcm);		\
+		} while (0)
+
 
 static inline
 struct bcm43xx_private * bcm43xx_priv(struct net_device *dev)
@@ -843,16 +887,6 @@ struct bcm43xx_radioinfo * bcm43xx_current_radio(struct bcm43xx_private *bcm)
 	return &(bcm->core_80211_ext[bcm->current_80211_core_idx].radio);
 }
 
-/* Are we running in init_board() context? */
-static inline
-int bcm43xx_is_initializing(struct bcm43xx_private *bcm)
-{
-	if (bcm->initialized)
-		return 0;
-	if (bcm->shutting_down)
-		return 0;
-	return 1;
-}
 
 static inline
 struct bcm43xx_lopair * bcm43xx_get_lopair(struct bcm43xx_phyinfo *phy,

drivers/net/wireless/bcm43xx/bcm43xx_debugfs.c

@@ -77,8 +77,8 @@ static ssize_t devinfo_read_file(struct file *file, char __user *userbuf,
 
 	down(&big_buffer_sem);
 
-	bcm43xx_lock_mmio(bcm, flags);
-	if (!bcm->initialized) {
+	bcm43xx_lock_irqsafe(bcm, flags);
+	if (bcm43xx_status(bcm) != BCM43xx_STAT_INITIALIZED) {
 		fappend("Board not initialized.\n");
 		goto out;
 	}
@@ -121,7 +121,7 @@ static ssize_t devinfo_read_file(struct file *file, char __user *userbuf,
 	fappend("\n");
 
 out:
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	res = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	up(&big_buffer_sem);
 	return res;
@@ -159,8 +159,8 @@ static ssize_t spromdump_read_file(struct file *file, char __user *userbuf,
 	unsigned long flags;
 
 	down(&big_buffer_sem);
-	bcm43xx_lock_mmio(bcm, flags);
-	if (!bcm->initialized) {
+	bcm43xx_lock_irqsafe(bcm, flags);
+	if (bcm43xx_status(bcm) != BCM43xx_STAT_INITIALIZED) {
 		fappend("Board not initialized.\n");
 		goto out;
 	}
@@ -169,7 +169,7 @@ static ssize_t spromdump_read_file(struct file *file, char __user *userbuf,
 	fappend("boardflags: 0x%04x\n", bcm->sprom.boardflags);
 
 out:
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	res = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	up(&big_buffer_sem);
 	return res;
@@ -188,8 +188,8 @@ static ssize_t tsf_read_file(struct file *file, char __user *userbuf,
 	u64 tsf;
 
 	down(&big_buffer_sem);
-	bcm43xx_lock_mmio(bcm, flags);
-	if (!bcm->initialized) {
+	bcm43xx_lock_irqsafe(bcm, flags);
+	if (bcm43xx_status(bcm) != BCM43xx_STAT_INITIALIZED) {
 		fappend("Board not initialized.\n");
 		goto out;
 	}
@@ -199,7 +199,7 @@ static ssize_t tsf_read_file(struct file *file, char __user *userbuf,
 		(unsigned int)(tsf & 0xFFFFFFFFULL));
 
 out:
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	res = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
 	up(&big_buffer_sem);
 	return res;
@@ -221,8 +221,8 @@ static ssize_t tsf_write_file(struct file *file, const char __user *user_buf,
 	        res = -EFAULT;
 		goto out_up;
 	}
-	bcm43xx_lock_mmio(bcm, flags);
-	if (!bcm->initialized) {
+	bcm43xx_lock_irqsafe(bcm, flags);
+	if (bcm43xx_status(bcm) != BCM43xx_STAT_INITIALIZED) {
 		printk(KERN_INFO PFX "debugfs: Board not initialized.\n");
 		res = -EFAULT;
 		goto out_unlock;
@@ -233,10 +233,11 @@ static ssize_t tsf_write_file(struct file *file, const char __user *user_buf,
 		goto out_unlock;
 	}
 	bcm43xx_tsf_write(bcm, tsf);
+	mmiowb();
 	res = buf_size;
 	
 out_unlock:
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 out_up:
 	up(&big_buffer_sem);
 	return res;
@@ -257,7 +258,7 @@ static ssize_t txstat_read_file(struct file *file, char __user *userbuf,
 	int i, cnt, j = 0;
 
 	down(&big_buffer_sem);
-	bcm43xx_lock(bcm, flags);
+	bcm43xx_lock_irqsafe(bcm, flags);
 
 	fappend("Last %d logged xmitstatus blobs (Latest first):\n\n",
 		BCM43xx_NR_LOGGED_XMITSTATUS);
@@ -293,14 +294,14 @@ static ssize_t txstat_read_file(struct file *file, char __user *userbuf,
 			i = BCM43xx_NR_LOGGED_XMITSTATUS - 1;
 	}
 
-	bcm43xx_unlock(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	res = simple_read_from_buffer(userbuf, count, ppos, buf, pos);
-	bcm43xx_lock(bcm, flags);
+	bcm43xx_lock_irqsafe(bcm, flags);
 	if (*ppos == pos) {
 		/* Done. Drop the copied data. */
 		e->xmitstatus_printing = 0;
 	}
-	bcm43xx_unlock(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	up(&big_buffer_sem);
 	return res;
 }

drivers/net/wireless/bcm43xx/bcm43xx_leds.c

@@ -51,12 +51,12 @@ static void bcm43xx_led_blink(unsigned long d)
 	struct bcm43xx_private *bcm = led->bcm;
 	unsigned long flags;
 
-	bcm43xx_lock_mmio(bcm, flags);
+	bcm43xx_lock_irqonly(bcm, flags);
 	if (led->blink_interval) {
 		bcm43xx_led_changestate(led);
 		mod_timer(&led->blink_timer, jiffies + led->blink_interval);
 	}
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqonly(bcm, flags);
 }
 
 static void bcm43xx_led_blink_start(struct bcm43xx_led *led,

drivers/net/wireless/bcm43xx/bcm43xx_phy.c

@@ -1648,7 +1648,7 @@ void bcm43xx_phy_set_baseband_attenuation(struct bcm43xx_private *bcm,
 void bcm43xx_phy_lo_g_measure(struct bcm43xx_private *bcm)
 {
 	static const u8 pairorder[10] = { 3, 1, 5, 7, 9, 2, 0, 4, 6, 8 };
-	const int is_initializing = bcm43xx_is_initializing(bcm);
+	const int is_initializing = (bcm43xx_status(bcm) == BCM43xx_STAT_INITIALIZING);
 	struct bcm43xx_phyinfo *phy = bcm43xx_current_phy(bcm);
 	struct bcm43xx_radioinfo *radio = bcm43xx_current_radio(bcm);
 	u16 h, i, oldi = 0, j;

drivers/net/wireless/bcm43xx/bcm43xx_pio.c

@@ -262,7 +262,7 @@ static void tx_tasklet(unsigned long d)
 	int err;
 	u16 txctl;
 
-	bcm43xx_lock_mmio(bcm, flags);
+	bcm43xx_lock_irqonly(bcm, flags);
 
 	txctl = bcm43xx_pio_read(queue, BCM43xx_PIO_TXCTL);
 	if (txctl & BCM43xx_PIO_TXCTL_SUSPEND)
@@ -298,7 +298,7 @@ static void tx_tasklet(unsigned long d)
 		continue;
 	}
 out_unlock:
-	bcm43xx_unlock_mmio(bcm, flags);
+	bcm43xx_unlock_irqonly(bcm, flags);
 }
 
 static void setup_txqueues(struct bcm43xx_pioqueue *queue)
@@ -374,7 +374,6 @@ static void cancel_transfers(struct bcm43xx_pioqueue *queue)
 	struct bcm43xx_pio_txpacket *packet, *tmp_packet;
 
 	netif_tx_disable(queue->bcm->net_dev);
-	assert(queue->bcm->shutting_down);
 	tasklet_disable(&queue->txtask);
 
 	list_for_each_entry_safe(packet, tmp_packet, &queue->txrunning, list)

drivers/net/wireless/bcm43xx/bcm43xx_sysfs.c

@@ -120,12 +120,12 @@ static ssize_t bcm43xx_attr_sprom_show(struct device *dev,
 			GFP_KERNEL);
 	if (!sprom)
 		return -ENOMEM;
-	bcm43xx_lock_mmio(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_irqsafe(bcm, flags);
 	err = bcm43xx_sprom_read(bcm, sprom);
 	if (!err)
 		err = sprom2hex(sprom, buf, PAGE_SIZE);
-	bcm43xx_unlock_mmio(bcm, flags);
+	mmiowb();
+	bcm43xx_unlock_irqsafe(bcm, flags);
 	kfree(sprom);
 
 	return err;
@@ -150,10 +150,10 @@ static ssize_t bcm43xx_attr_sprom_store(struct device *dev,
 	err = hex2sprom(sprom, buf, count);
 	if (err)
 		goto out_kfree;
-	bcm43xx_lock_mmio(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_irqsafe(bcm, flags);
 	err = bcm43xx_sprom_write(bcm, sprom);
-	bcm43xx_unlock_mmio(bcm, flags);
+	mmiowb();
+	bcm43xx_unlock_irqsafe(bcm, flags);
 out_kfree:
 	kfree(sprom);
 
@@ -170,15 +170,13 @@ static ssize_t bcm43xx_attr_interfmode_show(struct device *dev,
 					    char *buf)
 {
 	struct bcm43xx_private *bcm = dev_to_bcm(dev);
-	unsigned long flags;
 	int err;
 	ssize_t count = 0;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
-	bcm43xx_lock(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_noirq(bcm);
 
 	switch (bcm43xx_current_radio(bcm)->interfmode) {
 	case BCM43xx_RADIO_INTERFMODE_NONE:
@@ -195,7 +193,7 @@ static ssize_t bcm43xx_attr_interfmode_show(struct device *dev,
 	}
 	err = 0;
 
-	bcm43xx_unlock(bcm, flags);
+	bcm43xx_unlock_noirq(bcm);
 
 	return err ? err : count;
 
@@ -231,16 +229,15 @@ static ssize_t bcm43xx_attr_interfmode_store(struct device *dev,
 		return -EINVAL;
 	}
 
-	bcm43xx_lock_mmio(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_irqsafe(bcm, flags);
 
 	err = bcm43xx_radio_set_interference_mitigation(bcm, mode);
 	if (err) {
 		printk(KERN_ERR PFX "Interference Mitigation not "
 				    "supported by device\n");
 	}
-
-	bcm43xx_unlock_mmio(bcm, flags);
+	mmiowb();
+	bcm43xx_unlock_irqsafe(bcm, flags);
 
 	return err ? err : count;
 }
@@ -254,15 +251,13 @@ static ssize_t bcm43xx_attr_preamble_show(struct device *dev,
 					  char *buf)
 {
 	struct bcm43xx_private *bcm = dev_to_bcm(dev);
-	unsigned long flags;
 	int err;
 	ssize_t count;
 
 	if (!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
-	bcm43xx_lock(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_noirq(bcm);
 
 	if (bcm->short_preamble)
 		count = snprintf(buf, PAGE_SIZE, "1 (Short Preamble enabled)\n");
@@ -270,7 +265,7 @@ static ssize_t bcm43xx_attr_preamble_show(struct device *dev,
 		count = snprintf(buf, PAGE_SIZE, "0 (Short Preamble disabled)\n");
 
 	err = 0;
-	bcm43xx_unlock(bcm, flags);
+	bcm43xx_unlock_noirq(bcm);
 
 	return err ? err : count;
 }
@@ -290,13 +285,12 @@ static ssize_t bcm43xx_attr_preamble_store(struct device *dev,
 	value = get_boolean(buf, count);
 	if (value < 0)
 		return value;
-	bcm43xx_lock(bcm, flags);
-	assert(bcm->initialized);
+	bcm43xx_lock_irqsafe(bcm, flags);
 
 	bcm->short_preamble = !!value;
 
 	err = 0;
-	bcm43xx_unlock(bcm, flags);
+	bcm43xx_unlock_irqsafe(bcm, flags);
 
 	return err ? err : count;
 }
@@ -310,7 +304,7 @@ int bcm43xx_sysfs_register(struct bcm43xx_private *bcm)
 	struct device *dev = &bcm->pci_dev->dev;
 	int err;
 
-	assert(bcm->initialized);
+	assert(bcm43xx_status(bcm) == BCM43xx_STAT_INITIALIZED);
 
 	err = device_create_file(dev, &dev_attr_sprom);
 	if (err)