[PATCH 3.18 17/85] mwifiex: handle race during mwifiex_usb_disconnect

Greg Kroah-Hartman
2018-08-07T18:56:47Z

From: Ganapathi Bhat <gbhat@marvell.com>

[ 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>
---
drivers/net/wireless/mwifiex/usb.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/net/wireless/mwifiex/usb.c
+++ b/drivers/net/wireless/mwifiex/usb.c
@@ -556,6 +556,9 @@ static void mwifiex_usb_disconnect(struc
MWIFIEX_FUNC_SHUTDOWN);
}

+ if (adapter->workqueue)
+ flush_workqueue(adapter->workqueue);
+
mwifiex_usb_free(card);

dev_dbg(adapter->dev, "%s: removing card\n", __func__);