Re: [PATCH] fix oops in usbserial_cleanup function;

From: Greg KH
Date: Fri Oct 15 2010 - 00:20:22 EST


On Fri, Oct 15, 2010 at 11:50:56AM +0800, marui wrote:
> 1. I find this bug on OpenSUSE 11.3 which kernel vesion is 2.6.34, but the latest kernel vesion 2.6.36-rc7 aslo have this bug. This patch is based on the kernel of 2.6.36-rc7.
> 2. Bug report:
> a. Install huawei datacard dashboard on OpenSUSE 11.3
> b. Plug in huawei datacard into OpenSUSE 11.3 which kernel verison is 2.6.36-rc7
> c. After the dashboard has detected the device, I pull out the usb datacard
> d. close datashboard,then kernel panic will happen in usbserial_cleanup function.

What does the "dashboard" program do? Hold the port open?

> 3. fix the bug:
> I find usbserial_cleanup should judge the usb device wheher has been disconnected firtly.
>
>
> diff -uprN -X linux-2.6.36-rc7-orig/Documentation/dontdiff linux-2.6.36-rc7-orig/drivers/usb/serial/usb-serial.c linux-2.6.36-rc7/drivers/usb/serial/usb-serial.c
>
> --- linux-2.6.36-rc7_orig/drivers/usb/serial/usb-serial.c 2010-10-06 16:39:52.000000000 -0400
> +++ linux-2.6.36-rc7/drivers/usb/serial/usb-serial.c 2010-10-14 20:59:47.000000000 -0400
> @@ -328,6 +328,20 @@ static void serial_cleanup(struct tty_st
> /* The console is magical. Do not hang up the console hardware
> * or there will be tears.
> */
> + dbg("%s start\n",__func__);
> + if(NULL == port)
> + {
> + dbg("%s NULL == port\n",__func__);
> + return;

We don't need to keep the dbg statements here, do we?

> + }
> + mutex_lock(&port->serial->disc_mutex);
> + if (port->serial->disconnected)
> + {
> + dbg("%s port->serial->disconnected\n",__func__);
> + return_serial(port->serial);
> + return;

You can't return with a lock held.

> + }
> + mutex_unlock(&port->serial->disc_mutex);
> if (port->port.console)
> return;

Your tabs and spaces got all mixed up, and it can't be applied. Also, I
need a "Signed-off-by:" line to be able to accept it. Care to read the
file Documentation/SubmittingPatches for how to format a patch so we can
take it?

Also, run the patch through scripts/checkpatch.pl and resolve the coding
style issues before resending please.

thanks,

greg k-h
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