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mwifiex: fix corner case system hang issue

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Sometimes pending internal scan commands are delayed to give
preference to Tx traffic. 'scan_processing' flag has been
checked at the beginning of delay timer routine to know if in the
meantime scan operation has been cancelled.

There is a corner case where pending scan commands are emptied
after scan_processing flag check is passed. In this case
wrong pointer returned by list_first_entry() is passed to
list_del() which causes system hang.

This patch fixes the issue by adding list_empty() check.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Amitkumar Karwar 2014-07-11 20:53:14 -07:00 committed by John W. Linville
parent 2d702830e0
commit d5343f0690
1 changed files with 11 additions and 5 deletions
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16
drivers/net/wireless/mwifiex/main.c
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@ -33,6 +33,7 @@ static void scan_delay_timer_fn(unsigned long data)
struct mwifiex_private *priv = (struct mwifiex_private *)data;
struct mwifiex_adapter *adapter = priv->adapter;
struct cmd_ctrl_node *cmd_node, *tmp_node;
spinlock_t *scan_q_lock = &adapter->scan_pending_q_lock;
unsigned long flags;
if (adapter->surprise_removed)
@ -44,13 +45,13 @@ static void scan_delay_timer_fn(unsigned long data)
* Abort scan operation by cancelling all pending scan
* commands
*/
spin_lock_irqsave(&adapter->scan_pending_q_lock, flags);
spin_lock_irqsave(scan_q_lock, flags);
list_for_each_entry_safe(cmd_node, tmp_node,
&adapter->scan_pending_q, list) {
list_del(&cmd_node->list);
mwifiex_insert_cmd_to_free_q(adapter, cmd_node);
}
spin_unlock_irqrestore(&adapter->scan_pending_q_lock, flags);
spin_unlock_irqrestore(scan_q_lock, flags);
spin_lock_irqsave(&adapter->mwifiex_cmd_lock, flags);
adapter->scan_processing = false;
@ -79,12 +80,17 @@ static void scan_delay_timer_fn(unsigned long data)
*/
adapter->scan_delay_cnt = 0;
adapter->empty_tx_q_cnt = 0;
spin_lock_irqsave(&adapter->scan_pending_q_lock, flags);
spin_lock_irqsave(scan_q_lock, flags);
if (list_empty(&adapter->scan_pending_q)) {
spin_unlock_irqrestore(scan_q_lock, flags);
goto done;
}
cmd_node = list_first_entry(&adapter->scan_pending_q,
struct cmd_ctrl_node, list);
list_del(&cmd_node->list);
spin_unlock_irqrestore(&adapter->scan_pending_q_lock,
flags);
spin_unlock_irqrestore(scan_q_lock, flags);
mwifiex_insert_cmd_to_pending_q(adapter, cmd_node,
true);