2010-09-17 16:55:18

by Vipin Mehta

[permalink] [raw]
Subject: [PATCH] staging: ath6kl: Fixing a race condition during initialization

The commit fixes a race condition in the initialization portion of the
driver. The problem was observed while testing with the kernel in the
staging-next tree. The wait on the ready event is signalled prematurely
before setting the arVersion.wlan_ver and arVersion.abi_ver. The code
waiting on this semaphore checks for the validity of these values and
hence may proceed with an un-updated values of these fields. The wakeup
signal is now sent after these values are set.

Signed-off-by: Vipin Mehta <[email protected]>
---
drivers/staging/ath6kl/os/linux/ar6000_drv.c | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/ath6kl/os/linux/ar6000_drv.c b/drivers/staging/ath6kl/os/linux/ar6000_drv.c
index ff7976e..41d8842 100644
--- a/drivers/staging/ath6kl/os/linux/ar6000_drv.c
+++ b/drivers/staging/ath6kl/os/linux/ar6000_drv.c
@@ -4174,8 +4174,6 @@ ar6000_ready_event(void *devt, A_UINT8 *datap, A_UINT8 phyCap, A_UINT32 sw_ver,
AR_SOFTC_T *ar = (AR_SOFTC_T *)devt;
struct net_device *dev = ar->arNetDev;

- ar->arWmiReady = TRUE;
- wake_up(&arEvent);
A_MEMCPY(dev->dev_addr, datap, AR6000_ETH_ADDR_LEN);
AR_DEBUG_PRINTF(ATH_DEBUG_INFO,("mac address = %2.2x:%2.2x:%2.2x:%2.2x:%2.2x:%2.2x\n",
dev->dev_addr[0], dev->dev_addr[1],
@@ -4186,6 +4184,10 @@ ar6000_ready_event(void *devt, A_UINT8 *datap, A_UINT8 phyCap, A_UINT32 sw_ver,
ar->arVersion.wlan_ver = sw_ver;
ar->arVersion.abi_ver = abi_ver;

+ /* Indicate to the waiting thread that the ready event was received */
+ ar->arWmiReady = TRUE;
+ wake_up(&arEvent);
+
#if WLAN_CONFIG_IGNORE_POWER_SAVE_FAIL_EVENT_DURING_SCAN
wmi_pmparams_cmd(ar->arWmi, 0, 1, 0, 0, 1, IGNORE_POWER_SAVE_FAIL_EVENT_DURING_SCAN);
#endif
--
1.6.3.3