mfd: rtsx_usb: Avoid setting ucr->current_sg.status

BugLink: http://bugs.launchpad.net/bugs/1634153
commit 8dcc5ff8fcaf778bb57ab4448fedca9e381d088f upstream.

Member "status" of struct usb_sg_request is managed by usb core. A
spin lock is used to serialize the change of it. The driver could
check the value of req->status, but should avoid changing it without
the hold of the spinlock. Otherwise, it could cause race or error
in usb core.

This patch could be backported to stable kernels with version later
than v3.14.

Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Roger Tseng <rogerable@realtek.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/drivers/mfd/rtsx_usb.c b/drivers/mfd/rtsx_usb.c
index dbd907d7170ebe990cb63fede374624ea03b6fd4..691dab791f7af81d91ed3892a945c74c1f0d3fa1 100644 (file)
--- a/drivers/mfd/rtsx_usb.c
+++ b/drivers/mfd/rtsx_usb.c
@@ -46,9 +46,6 @@ static void rtsx_usb_sg_timed_out(unsigned long data)
 
        dev_dbg(&ucr->pusb_intf->dev, "%s: sg transfer timed out", __func__);
        usb_sg_cancel(&ucr->current_sg);
-
-       /* we know the cancellation is caused by time-out */
-       ucr->current_sg.status = -ETIMEDOUT;
 }
 
 static int rtsx_usb_bulk_transfer_sglist(struct rtsx_ucr *ucr,
@@ -67,12 +64,15 @@ static int rtsx_usb_bulk_transfer_sglist(struct rtsx_ucr *ucr,
        ucr->sg_timer.expires = jiffies + msecs_to_jiffies(timeout);
        add_timer(&ucr->sg_timer);
        usb_sg_wait(&ucr->current_sg);
-       del_timer_sync(&ucr->sg_timer);
+       if (!del_timer_sync(&ucr->sg_timer))
+               ret = -ETIMEDOUT;
+       else
+               ret = ucr->current_sg.status;
 
        if (act_len)
                *act_len = ucr->current_sg.bytes;
 
-       return ucr->current_sg.status;
+       return ret;
 }
 
 int rtsx_usb_transfer_data(struct rtsx_ucr *ucr, unsigned int pipe,