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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH 4.18 124/235] usb: host: u132-hcd: Fix a sleep-in-atomic-context bug in u132_get_frame()
Date:   Mon, 24 Sep 2018 13:51:50 +0200
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jia-Ju Bai <baijiaju1990@gmail.com>

commit 6d4f268fa132742fe96dad22307c68d237356d88 upstream.

i_usX2Y_subs_startup in usbusx2yaudio.c is a completion handler function
for the USB driver. So it should not sleep, but it is can sleep
according to the function call paths (from bottom to top) in Linux-4.16.

[FUNC] msleep
drivers/usb/host/u132-hcd.c, 2558:
	msleep in u132_get_frame
drivers/usb/core/hcd.c, 2231:
	[FUNC_PTR]u132_get_frame in usb_hcd_get_frame_number
drivers/usb/core/usb.c, 822:
	usb_hcd_get_frame_number in usb_get_current_frame_number
sound/usb/usx2y/usbusx2yaudio.c, 303:
	usb_get_current_frame_number in i_usX2Y_urb_complete
sound/usb/usx2y/usbusx2yaudio.c, 366:
	i_usX2Y_urb_complete in i_usX2Y_subs_startup

Note that [FUNC_PTR] means a function pointer call is used.

To fix this bug, msleep() is replaced with mdelay().

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/host/u132-hcd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/host/u132-hcd.c
+++ b/drivers/usb/host/u132-hcd.c
@@ -2555,7 +2555,7 @@ static int u132_get_frame(struct usb_hcd
 	} else {
 		int frame = 0;
 		dev_err(&u132->platform_dev->dev, "TODO: u132_get_frame\n");
-		msleep(100);
+		mdelay(100);
 		return frame;
 	}
 }