Re: rt8192cu on USB3

[Larry Finger <Larry.Finger@lwfinger.net>]

On 03/09/2012 01:39 AM, jerome huang wrote:
>
> Are other patches recommend besides b0302a?

That is the main one. Others that you might consider, but they probably will not 
make any difference:

3eda95d rtlwifi: Remove extra debugging message accidentally left in

4e3c3b8 rtlwifi: Fix breakage in debug functions when built as a module
           This fixes a problem caused in commit 481b9606.

ebecdcc rtlwifi: rtl8192c: Prevent sleeping from invalid context in rtl8192cu

The patch below is currently under test. It is not likely to make any difference 
with your problem, but it changes USB reads a lot.

Larry

========================================================================

The current version of rtlwifi for USB operations uses kmalloc to
acquire a 32-bit buffer for reading. When _usb_read_sync() is called
with the rcu_lock held, the result is a "sleeping function called
from invalid context" BUG. This is reported for two cases in
https://bugzilla.kernel.org/show_bug.cgi?id=42775. The first case
where the lock originates from within rtlwifi and could be fixed
by rearranging the locking; however, the second originates from
within mac80211. The kmalloc() call is removed from _usb_read_sync()
by creating a ring buffer pointer in the private area and
allocating the buffer data in the probe routine.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org> [This version good for 3.3+ - different 
patch for 3.2 - 2.6.39]
---

Index: wireless-testing-new/drivers/net/wireless/rtlwifi/usb.c
===================================================================
--- wireless-testing-new.orig/drivers/net/wireless/rtlwifi/usb.c
+++ wireless-testing-new/drivers/net/wireless/rtlwifi/usb.c
@@ -124,46 +124,38 @@ static int _usbctrl_vendorreq_sync_read(
  	return status;
  }

-static u32 _usb_read_sync(struct usb_device *udev, u32 addr, u16 len)
+static u32 _usb_read_sync(struct rtl_priv *rtlpriv, u32 addr, u16 len)
  {
+	struct device *dev = rtlpriv->io.dev;
+	struct usb_device *udev = to_usb_device(dev);
  	u8 request;
  	u16 wvalue;
  	u16 index;
-	u32 *data;
-	u32 ret;
+	__le32 *data = &rtlpriv->usb_data[rtlpriv->usb_data_index];

-	data = kmalloc(sizeof(u32), GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
  	request = REALTEK_USB_VENQT_CMD_REQ;
  	index = REALTEK_USB_VENQT_CMD_IDX; /* n/a */

  	wvalue = (u16)addr;
  	_usbctrl_vendorreq_sync_read(udev, request, wvalue, index, data, len);
-	ret = le32_to_cpu(*data);
-	kfree(data);
-	return ret;
+	if (++rtlpriv->usb_data_index >= RTL_USB_MAX_RX_COUNT)
+		rtlpriv->usb_data_index = 0;
+	return le32_to_cpu(*data);
  }

  static u8 _usb_read8_sync(struct rtl_priv *rtlpriv, u32 addr)
  {
-	struct device *dev = rtlpriv->io.dev;
-
-	return (u8)_usb_read_sync(to_usb_device(dev), addr, 1);
+	return (u8)_usb_read_sync(rtlpriv, addr, 1);
  }

  static u16 _usb_read16_sync(struct rtl_priv *rtlpriv, u32 addr)
  {
-	struct device *dev = rtlpriv->io.dev;
-
-	return (u16)_usb_read_sync(to_usb_device(dev), addr, 2);
+	return (u16)_usb_read_sync(rtlpriv, addr, 2);
  }

  static u32 _usb_read32_sync(struct rtl_priv *rtlpriv, u32 addr)
  {
-	struct device *dev = rtlpriv->io.dev;
-
-	return _usb_read_sync(to_usb_device(dev), addr, 4);
+	return _usb_read_sync(rtlpriv, addr, 4);
  }

  static void _usb_write_async(struct usb_device *udev, u32 addr, u32 val,
@@ -951,6 +943,13 @@ int __devinit rtl_usb_probe(struct usb_i
  		return -ENOMEM;
  	}
  	rtlpriv = hw->priv;
+	rtlpriv->usb_data = kzalloc(RTL_USB_MAX_RX_COUNT * sizeof(u32),
+				    GFP_KERNEL);
+	if (!rtlpriv->usb_data) {
+		RT_ASSERT(false, "USB data buffer allocation failed\n");
+		return -ENOMEM;
+	}
+	rtlpriv->usb_data_index = 0;
  	init_completion(&rtlpriv->firmware_loading_complete);
  	SET_IEEE80211_DEV(hw, &intf->dev);
  	udev = interface_to_usbdev(intf);
@@ -1019,6 +1018,7 @@ void rtl_usb_disconnect(struct usb_inter
  	/* rtl_deinit_rfkill(hw); */
  	rtl_usb_deinit(hw);
  	rtl_deinit_core(hw);
+	kfree(rtlpriv->usb_data);
  	rtlpriv->cfg->ops->deinit_sw_leds(hw);
  	rtlpriv->cfg->ops->deinit_sw_vars(hw);
  	_rtl_usb_io_handler_release(hw);
Index: wireless-testing-new/drivers/net/wireless/rtlwifi/wifi.h
===================================================================
--- wireless-testing-new.orig/drivers/net/wireless/rtlwifi/wifi.h
+++ wireless-testing-new/drivers/net/wireless/rtlwifi/wifi.h
@@ -67,7 +67,7 @@
  #define QOS_QUEUE_NUM				4
  #define RTL_MAC80211_NUM_QUEUE			5
  #define REALTEK_USB_VENQT_MAX_BUF_SIZE		254
-
+#define RTL_USB_MAX_RX_COUNT			100
  #define QBSS_LOAD_SIZE				5
  #define MAX_WMMELE_LENGTH			64

@@ -1629,6 +1629,10 @@ struct rtl_priv {
  	   interface or hardware */
  	unsigned long status;

+	/* data buffer pointer for USB reads */
+	__le32 *usb_data;
+	int usb_data_index;
+
  	/*This must be the last item so
  	   that it points to the data allocated
  	   beyond  this structure like: