mwifiex: handle race during mwifiex_usb_disconnect

[ Upstream commit b817047ae70c0bd67b677b65d0d69d72cd6e9728 ]

Race condition is observed during rmmod of mwifiex_usb:

1. The rmmod thread will call mwifiex_usb_disconnect(), download
   SHUTDOWN command and do wait_event_interruptible_timeout(),
   waiting for response.

2. The main thread will handle the response and will do a
   wake_up_interruptible(), unblocking rmmod thread.

3. On getting unblocked, rmmod thread  will make rx_cmd.urb = NULL in
   mwifiex_usb_free().

4. The main thread will try to resubmit rx_cmd.urb in
   mwifiex_usb_submit_rx_urb(), which is NULL.

To fix, wait for main thread to complete before calling
mwifiex_usb_free().

Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/wireless/mwifiex/usb.c b/drivers/net/wireless/mwifiex/usb.c
index 4371e12b36f38af6e0946969288ce918dc8487b1..3f239f1ad203fe738e28af0bd544f4c7c147c1d2 100644 (file)
--- a/drivers/net/wireless/mwifiex/usb.c
+++ b/drivers/net/wireless/mwifiex/usb.c
@@ -556,6 +556,9 @@ static void mwifiex_usb_disconnect(struct usb_interface *intf)
                                         MWIFIEX_FUNC_SHUTDOWN);
        }
 
+       if (adapter->workqueue)
+               flush_workqueue(adapter->workqueue);
+
        mwifiex_usb_free(card);
 
        dev_dbg(adapter->dev, "%s: removing card\n", __func__);