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Date: Wed, 11 Nov 2009 18:02:29 -0600
From: Larry Finger <Larry.Finger@lwfinger.net>
To: John W Linville <linville@tuxdriver.com>, chunkeey@web.de
Cc: linux-wireless@vger.kernel.org
Subject: [PATCH V2] p54usb: Remove DMA buffer from stack
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On 2.6.32-rc6 from wireless-testing, the following warning is emitted:

------------[ cut here ]------------ 
WARNING: at lib/dma-debug.c:860 check_for_stack+0xaa/0xe0() 
Hardware name: HP Pavilion dv2700 Notebook PC 
ehci_hcd 0000:00:02.1: DMA-API: device driver maps memory fromstack
	 [addr=ffff8800b6e2bca8] 
Modules linked in: <Removed> 
Pid: 16378, comm: modprobe Not tainted 2.6.32-rc6-wl #244 
Call Trace: 
 [<ffffffff81049698>] warn_slowpath_common+0x78/0xb0 
 [<ffffffff8104972c>] warn_slowpath_fmt+0x3c/0x40 
 [<ffffffff811ae52a>] check_for_stack+0xaa/0xe0 
 [<ffffffff811afc8d>] debug_dma_map_page+0xfd/0x170 
 [<ffffffffa006297a>] usb_hcd_submit_urb+0x3da/0x9c0 [usbcore] 
 [<ffffffff81076e6f>] ? lockdep_init_map+0x5f/0x5d0 
 [<ffffffffa0063365>] usb_submit_urb+0xe5/0x260 [usbcore] 
 [<ffffffffa0064b7e>] usb_start_wait_urb+0x5e/0xf0 [usbcore] 
 [<ffffffffa0063943>] ? usb_init_urb+0x23/0x40 [usbcore] 
 [<ffffffffa0064cd4>] usb_bulk_msg+0xc4/0x150 [usbcore] 
 [<ffffffffa0441a91>] T.719+0x31/0x40 [p54usb] 
 [<ffffffffa0441acf>] p54u_upload_firmware_3887+0x2f/0x490 [p54usb] 
 [<ffffffffa049c667>] ? p54_parse_firmware+0x427/0x450 [p54common] 
 <Rest of traceback removed>
---[ end trace f77df0316ddad3de ]--- 

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.org>
---

John,

This is 2.6.32 material. Sorry to find it so late in the rc cycle. I hop
DaveM doesn't give you too much trouble.

V2 - Fix line wraps in trace back.

Larry
---

Index: wireless-testing/drivers/net/wireless/p54/p54usb.c
===================================================================
--- wireless-testing.orig/drivers/net/wireless/p54/p54usb.c
+++ wireless-testing/drivers/net/wireless/p54/p54usb.c
@@ -426,12 +426,16 @@ static const char p54u_romboot_3887[] =
 static int p54u_firmware_reset_3887(struct ieee80211_hw *dev)
 {
 	struct p54u_priv *priv = dev->priv;
-	u8 buf[4];
+	u8 *buf;
 	int ret;
 
-	memcpy(&buf, p54u_romboot_3887, sizeof(buf));
+	buf = kmalloc(4, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+ 	memcpy(buf, p54u_romboot_3887, 4);
 	ret = p54u_bulk_msg(priv, P54U_PIPE_DATA,
-			    buf, sizeof(buf));
+			    buf, 4);
+	kfree(buf);
 	if (ret)
 		dev_err(&priv->udev->dev, "(p54usb) unable to jump to "
 			"boot ROM (%d)!\n", ret);