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Date: Mon, 28 May 2012 04:13:48 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
alan@...rguk.ukuu.org.uk, Larry Finger <Larry.Finger@...inger.net>,
"John W. Linville" <linville@...driver.com>
Subject: [ 106/117] rtlwifi: Preallocate USB read buffers and eliminate kalloc in read routine
3.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Larry Finger <Larry.Finger@...inger.net>
commit a7959c1394d4126a70a53b914ce4105f5173d0aa upstream.
The current version of rtlwifi for USB operations uses kmalloc to
acquire a 32-bit buffer for each read of the device. 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 has the lock originating 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@...inger.net>
Signed-off-by: John W. Linville <linville@...driver.com>
[This version will apply to 3.2 and earlier. - Larry]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/net/wireless/rtlwifi/usb.c
+++ b/drivers/net/wireless/rtlwifi/usb.c
@@ -113,46 +113,38 @@
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 = *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,
@@ -913,6 +905,11 @@
return -ENOMEM;
}
rtlpriv = hw->priv;
+ rtlpriv->usb_data = kzalloc(RTL_USB_MAX_RX_COUNT * sizeof(u32),
+ GFP_KERNEL);
+ if (!rtlpriv->usb_data)
+ return -ENOMEM;
+ rtlpriv->usb_data_index = 0;
SET_IEEE80211_DEV(hw, &intf->dev);
udev = interface_to_usbdev(intf);
usb_get_dev(udev);
@@ -990,6 +987,7 @@
/* 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);
--- a/drivers/net/wireless/rtlwifi/wifi.h
+++ b/drivers/net/wireless/rtlwifi/wifi.h
@@ -63,7 +63,7 @@
#define AC_MAX 4
#define QOS_QUEUE_NUM 4
#define RTL_MAC80211_NUM_QUEUE 5
-
+#define RTL_USB_MAX_RX_COUNT 100
#define QBSS_LOAD_SIZE 5
#define MAX_WMMELE_LENGTH 64
@@ -1621,6 +1621,10 @@
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:
--
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