rtlwifi: rtl8192cu: Change buffer allocation for synchronous reads

In commit a7959c1, the USB part of rtlwifi was switched to convert
_usb_read_sync() to using a preallocated buffer rather than one
that has been acquired using kmalloc. Although this routine is named
as though it were synchronous, there seem to be simultaneous users,
and the selection of the index to the data buffer is not multi-user
safe. This situation is addressed by adding a new spinlock. The routine
cannot sleep, thus a mutex is not allowed.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/net/wireless/rtlwifi/wifi.h b/drivers/net/wireless/rtlwifi/wifi.h
index bd816aef26dc..cdaa21f29710 100644
--- a/drivers/net/wireless/rtlwifi/wifi.h
+++ b/drivers/net/wireless/rtlwifi/wifi.h
@@ -1555,6 +1555,7 @@ struct rtl_locks {
         spinlock_t rf_ps_lock;
         spinlock_t rf_lock;
         spinlock_t waitq_lock;
+        spinlock_t usb_lock;
 
         /*Dual mac*/
         spinlock_t cck_and_rw_pagea_lock;