rt2x00: Fix race condition when using inderect registers

Indirect registers require multiple calls to the CSR register in order to access the indirect registers. This must be protected under a lock to prevent race conditions which could cause invalid data to be returned when reading from the indirect register or silent failures when writing data to the indirect register. USB drivers where already protected under a mutex, so rename the mutex and make PCI drivers use the mutex as well. This now means that BBP and RF registers are no longer accessible in interrupt context. That is not a bad situation since the slow behavior of accessing those registers means we don't _want_ to access them in interrupt context either. Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com> Signed-off-by: John W. Linville <linville@tuxdriver.com>
git-mirror · Nov 21, 2008 · 8ff48a8 · 8ff48a8
1 parent bad1363
commit 8ff48a8
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Showing 8 changed files with 152 additions and 81 deletions.
diff --git a/drivers/net/wireless/rt2x00/rt2400pci.c b/drivers/net/wireless/rt2x00/rt2400pci.c
@@ -69,14 +69,14 @@ static void rt2400pci_bbp_write(struct rt2x00_dev *rt2x00dev,
 {
 	u32 reg;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	/*
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2400pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Write failed.\n");
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	/*
 	 * Write the data into the BBP.
@@ -88,21 +88,30 @@ static void rt2400pci_bbp_write(struct rt2x00_dev *rt2x00dev,
 	rt2x00_set_field32(&reg, BBPCSR_WRITE_CONTROL, 1);
 
 	rt2x00pci_register_write(rt2x00dev, BBPCSR, reg);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	return;
+
+exit_fail:
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	ERROR(rt2x00dev, "BBPCSR register busy. Write failed.\n");
 }
 
 static void rt2400pci_bbp_read(struct rt2x00_dev *rt2x00dev,
 			       const unsigned int word, u8 *value)
 {
 	u32 reg;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	/*
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2400pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	/*
 	 * Write the request into the BBP.
@@ -118,13 +127,20 @@ static void rt2400pci_bbp_read(struct rt2x00_dev *rt2x00dev,
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2400pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
-		*value = 0xff;
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	*value = rt2x00_get_field32(reg, BBPCSR_VALUE);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	return;
+
+exit_fail:
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
+	*value = 0xff;
 }
 
 static void rt2400pci_rf_write(struct rt2x00_dev *rt2x00dev,
@@ -136,13 +152,16 @@ static void rt2400pci_rf_write(struct rt2x00_dev *rt2x00dev,
 	if (!word)
 		return;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
 		rt2x00pci_register_read(rt2x00dev, RFCSR, &reg);
 		if (!rt2x00_get_field32(reg, RFCSR_BUSY))
 			goto rf_write;
 		udelay(REGISTER_BUSY_DELAY);
 	}
 
+	mutex_unlock(&rt2x00dev->csr_mutex);
 	ERROR(rt2x00dev, "RFCSR register busy. Write failed.\n");
 	return;
 
@@ -155,6 +174,8 @@ static void rt2400pci_rf_write(struct rt2x00_dev *rt2x00dev,
 
 	rt2x00pci_register_write(rt2x00dev, RFCSR, reg);
 	rt2x00_rf_write(rt2x00dev, word, value);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
 }
 
 static void rt2400pci_eepromregister_read(struct eeprom_93cx6 *eeprom)

diff --git a/drivers/net/wireless/rt2x00/rt2500pci.c b/drivers/net/wireless/rt2x00/rt2500pci.c
@@ -69,14 +69,14 @@ static void rt2500pci_bbp_write(struct rt2x00_dev *rt2x00dev,
 {
 	u32 reg;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	/*
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2500pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Write failed.\n");
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	/*
 	 * Write the data into the BBP.
@@ -88,21 +88,30 @@ static void rt2500pci_bbp_write(struct rt2x00_dev *rt2x00dev,
 	rt2x00_set_field32(&reg, BBPCSR_WRITE_CONTROL, 1);
 
 	rt2x00pci_register_write(rt2x00dev, BBPCSR, reg);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	return;
+
+exit_fail:
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	ERROR(rt2x00dev, "BBPCSR register busy. Write failed.\n");
 }
 
 static void rt2500pci_bbp_read(struct rt2x00_dev *rt2x00dev,
 			       const unsigned int word, u8 *value)
 {
 	u32 reg;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	/*
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2500pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	/*
 	 * Write the request into the BBP.
@@ -118,13 +127,20 @@ static void rt2500pci_bbp_read(struct rt2x00_dev *rt2x00dev,
 	 * Wait until the BBP becomes ready.
 	 */
 	reg = rt2500pci_bbp_check(rt2x00dev);
-	if (rt2x00_get_field32(reg, BBPCSR_BUSY)) {
-		ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
-		*value = 0xff;
-		return;
-	}
+	if (rt2x00_get_field32(reg, BBPCSR_BUSY))
+		goto exit_fail;
 
 	*value = rt2x00_get_field32(reg, BBPCSR_VALUE);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	return;
+
+exit_fail:
+	mutex_unlock(&rt2x00dev->csr_mutex);
+
+	ERROR(rt2x00dev, "BBPCSR register busy. Read failed.\n");
+	*value = 0xff;
 }
 
 static void rt2500pci_rf_write(struct rt2x00_dev *rt2x00dev,
@@ -136,13 +152,16 @@ static void rt2500pci_rf_write(struct rt2x00_dev *rt2x00dev,
 	if (!word)
 		return;
 
+	mutex_lock(&rt2x00dev->csr_mutex);
+
 	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
 		rt2x00pci_register_read(rt2x00dev, RFCSR, &reg);
 		if (!rt2x00_get_field32(reg, RFCSR_BUSY))
 			goto rf_write;
 		udelay(REGISTER_BUSY_DELAY);
 	}
 
+	mutex_unlock(&rt2x00dev->csr_mutex);
 	ERROR(rt2x00dev, "RFCSR register busy. Write failed.\n");
 	return;
 
@@ -155,6 +174,8 @@ static void rt2500pci_rf_write(struct rt2x00_dev *rt2x00dev,
 
 	rt2x00pci_register_write(rt2x00dev, RFCSR, reg);
 	rt2x00_rf_write(rt2x00dev, word, value);
+
+	mutex_unlock(&rt2x00dev->csr_mutex);
 }
 
 static void rt2500pci_eepromregister_read(struct eeprom_93cx6 *eeprom)

diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c
@@ -47,7 +47,7 @@
  * between each attampt. When the busy bit is still set at that time,
  * the access attempt is considered to have failed,
  * and we will print an error.
- * If the usb_cache_mutex is already held then the _lock variants must
+ * If the csr_mutex is already held then the _lock variants must
  * be used instead.
  */
 static inline void rt2500usb_register_read(struct rt2x00_dev *rt2x00dev,
@@ -132,7 +132,7 @@ static void rt2500usb_bbp_write(struct rt2x00_dev *rt2x00dev,
 {
 	u16 reg;
 
-	mutex_lock(&rt2x00dev->usb_cache_mutex);
+	mutex_lock(&rt2x00dev->csr_mutex);
 
 	/*
 	 * Wait until the BBP becomes ready.
@@ -151,12 +151,12 @@ static void rt2500usb_bbp_write(struct rt2x00_dev *rt2x00dev,
 
 	rt2500usb_register_write_lock(rt2x00dev, PHY_CSR7, reg);
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	return;
 
 exit_fail:
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	ERROR(rt2x00dev, "PHY_CSR8 register busy. Write failed.\n");
 }
@@ -166,7 +166,7 @@ static void rt2500usb_bbp_read(struct rt2x00_dev *rt2x00dev,
 {
 	u16 reg;
 
-	mutex_lock(&rt2x00dev->usb_cache_mutex);
+	mutex_lock(&rt2x00dev->csr_mutex);
 
 	/*
 	 * Wait until the BBP becomes ready.
@@ -194,12 +194,12 @@ static void rt2500usb_bbp_read(struct rt2x00_dev *rt2x00dev,
 	rt2500usb_register_read_lock(rt2x00dev, PHY_CSR7, &reg);
 	*value = rt2x00_get_field16(reg, PHY_CSR7_DATA);
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	return;
 
 exit_fail:
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	ERROR(rt2x00dev, "PHY_CSR8 register busy. Read failed.\n");
 	*value = 0xff;
@@ -214,7 +214,7 @@ static void rt2500usb_rf_write(struct rt2x00_dev *rt2x00dev,
 	if (!word)
 		return;
 
-	mutex_lock(&rt2x00dev->usb_cache_mutex);
+	mutex_lock(&rt2x00dev->csr_mutex);
 
 	for (i = 0; i < REGISTER_BUSY_COUNT; i++) {
 		rt2500usb_register_read_lock(rt2x00dev, PHY_CSR10, &reg);
@@ -223,7 +223,7 @@ static void rt2500usb_rf_write(struct rt2x00_dev *rt2x00dev,
 		udelay(REGISTER_BUSY_DELAY);
 	}
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 	ERROR(rt2x00dev, "PHY_CSR10 register busy. Write failed.\n");
 	return;
 
@@ -241,7 +241,7 @@ static void rt2500usb_rf_write(struct rt2x00_dev *rt2x00dev,
 	rt2500usb_register_write_lock(rt2x00dev, PHY_CSR10, reg);
 	rt2x00_rf_write(rt2x00dev, word, value);
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 }
 
 #ifdef CONFIG_RT2X00_LIB_DEBUGFS

diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -746,16 +746,15 @@ struct rt2x00_dev {
 	} csr;
 
 	/*
-	 * Mutex to protect register accesses on USB devices.
-	 * There are 2 reasons this is needed, one is to ensure
-	 * use of the csr_cache (for USB devices) by one thread
-	 * isn't corrupted by another thread trying to access it.
-	 * The other is that access to BBP and RF registers
-	 * require multiple BUS transactions and if another thread
-	 * attempted to access one of those registers at the same
-	 * time one of the writes could silently fail.
-	 */
-	struct mutex usb_cache_mutex;
+	 * Mutex to protect register accesses.
+	 * For PCI and USB devices it protects against concurrent indirect
+	 * register access (BBP, RF, MCU) since accessing those
+	 * registers require multiple calls to the CSR registers.
+	 * For USB devices it also protects the csr_cache since that
+	 * field is used for normal CSR access and it cannot support
+	 * multiple callers simultaneously.
+	 */
+	struct mutex csr_mutex;
 
 	/*
 	 * Current packet filter configuration for the device.

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -1051,6 +1051,8 @@ int rt2x00lib_probe_dev(struct rt2x00_dev *rt2x00dev)
 {
 	int retval = -ENOMEM;
 
+	mutex_init(&rt2x00dev->csr_mutex);
+
 	/*
 	 * Make room for rt2x00_intf inside the per-interface
 	 * structure ieee80211_vif.

diff --git a/drivers/net/wireless/rt2x00/rt2x00usb.c b/drivers/net/wireless/rt2x00/rt2x00usb.c
@@ -79,7 +79,7 @@ int rt2x00usb_vendor_req_buff_lock(struct rt2x00_dev *rt2x00dev,
 {
 	int status;
 
-	BUG_ON(!mutex_is_locked(&rt2x00dev->usb_cache_mutex));
+	BUG_ON(!mutex_is_locked(&rt2x00dev->csr_mutex));
 
 	/*
 	 * Check for Cache availability.
@@ -110,13 +110,13 @@ int rt2x00usb_vendor_request_buff(struct rt2x00_dev *rt2x00dev,
 {
 	int status;
 
-	mutex_lock(&rt2x00dev->usb_cache_mutex);
+	mutex_lock(&rt2x00dev->csr_mutex);
 
 	status = rt2x00usb_vendor_req_buff_lock(rt2x00dev, request,
 						requesttype, offset, buffer,
 						buffer_length, timeout);
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	return status;
 }
@@ -132,7 +132,7 @@ int rt2x00usb_vendor_request_large_buff(struct rt2x00_dev *rt2x00dev,
 	unsigned char *tb;
 	u16 off, len, bsize;
 
-	mutex_lock(&rt2x00dev->usb_cache_mutex);
+	mutex_lock(&rt2x00dev->csr_mutex);
 
 	tb  = (char *)buffer;
 	off = offset;
@@ -148,7 +148,7 @@ int rt2x00usb_vendor_request_large_buff(struct rt2x00_dev *rt2x00dev,
 		off += bsize;
 	}
 
-	mutex_unlock(&rt2x00dev->usb_cache_mutex);
+	mutex_unlock(&rt2x00dev->csr_mutex);
 
 	return status;
 }
@@ -531,7 +531,6 @@ int rt2x00usb_probe(struct usb_interface *usb_intf,
 	rt2x00dev->dev = &usb_intf->dev;
 	rt2x00dev->ops = ops;
 	rt2x00dev->hw = hw;
-	mutex_init(&rt2x00dev->usb_cache_mutex);
 
 	rt2x00dev->usb_maxpacket =
 	    usb_maxpacket(usb_dev, usb_sndbulkpipe(usb_dev, 1), 1);