2009-03-28 00:46:19

by Christian Lamparter

[permalink] [raw]
Subject: [PATCH] ar9170: fix hang on stop

This patch fixes a locking problem which freezes the network core.

The deadlock goes as follows:
- ar9170_op_stop - is called
1. change the state to IDLE
2. > take the MUTEX <
3. cancel_SYNC all pending work, which means
"block until a work_struct's callback has terminated"
=> if filter_config_work was queued it tries to get the MUTEX,
before checking the device state...

Signed-off-by: Christian Lamparter <[email protected]>
---
John,

I guess you have to queue this for the next wireless-2.6 ;)
By the way, I guess you should add the p54spi fixes as well.

Regards,
Chr
---
diff --git a/drivers/net/wireless/ar9170/main.c b/drivers/net/wireless/ar9170/main.c
index 5996ff9..5f55754 100644
--- a/drivers/net/wireless/ar9170/main.c
+++ b/drivers/net/wireless/ar9170/main.c
@@ -742,8 +742,9 @@ static void ar9170_op_stop(struct ieee80211_hw *hw)
if (IS_STARTED(ar))
ar->state = AR9170_IDLE;

- mutex_lock(&ar->mutex);
+ flush_workqueue(ar->hw->workqueue);

+ mutex_lock(&ar->mutex);
cancel_delayed_work_sync(&ar->tx_status_janitor);
cancel_work_sync(&ar->filter_config_work);
cancel_work_sync(&ar->beacon_work);
@@ -1123,10 +1124,10 @@ static void ar9170_set_filters(struct work_struct *work)
filter_config_work);
int err;

- mutex_lock(&ar->mutex);
if (unlikely(!IS_STARTED(ar)))
- goto unlock;
+ return ;

+ mutex_lock(&ar->mutex);
if (ar->filter_changed & AR9170_FILTER_CHANGED_PROMISC) {
err = ar9170_set_operating_mode(ar);
if (err)