iwlwifi: fix race condition during driver unload

This patch fixed the OOPS when load the driver while rf-kill is on then
unload the driver right after load. a race condition caused the interupt
handler to schedule the tasklet which will run right after the driver pci_remove
causing invalid poiter OOPS.

Signed-off-by: Mohamed Abbas <mabbas@linux.intel.com>
Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 32 insertions, 2 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index ab635dcfd5d..2a5245b63e3 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -4153,6 +4153,16 @@ static void iwl3945_enable_interrupts(struct iwl3945_priv *priv)
 	iwl3945_write32(priv, CSR_INT_MASK, CSR_INI_SET_MASK);
 }
 
+
+/* call this function to flush any scheduled tasklet */
+static inline void iwl_synchronize_irq(struct iwl3945_priv *priv)
+{
+	/* wait to make sure we flush pedding tasklet*/
+	synchronize_irq(priv->pci_dev->irq);
+	tasklet_kill(&priv->irq_tasklet);
+}
+
+
 static inline void iwl3945_disable_interrupts(struct iwl3945_priv *priv)
 {
 	clear_bit(STATUS_INT_ENABLED, &priv->status);
@@ -4552,7 +4562,9 @@ static void iwl3945_irq_tasklet(struct iwl3945_priv *priv)
 	}
 
 	/* Re-enable all interrupts */
-	iwl3945_enable_interrupts(priv);
+	/* only Re-enable if disabled by irq */
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		iwl3945_enable_interrupts(priv);
 
 #ifdef CONFIG_IWL3945_DEBUG
 	if (iwl3945_debug_level & (IWL_DL_ISR)) {
@@ -4616,7 +4628,9 @@ unplugged:
 
  none:
 	/* re-enable interrupts here since we don't have anything to service. */
-	iwl3945_enable_interrupts(priv);
+	/* only Re-enable if disabled by irq */
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		iwl3945_enable_interrupts(priv);
 	spin_unlock(&priv->lock);
 	return IRQ_NONE;
 }
@@ -5905,7 +5919,10 @@ static void __iwl3945_down(struct iwl3945_priv *priv)
 	iwl3945_write32(priv, CSR_RESET, CSR_RESET_REG_FLAG_NEVO_RESET);
 
 	/* tell the device to stop sending interrupts */
+	spin_lock_irqsave(&priv->lock, flags);
 	iwl3945_disable_interrupts(priv);
+	spin_unlock_irqrestore(&priv->lock, flags);
+	iwl_synchronize_irq(priv);
 
 	if (priv->mac80211_registered)
 		ieee80211_stop_queues(priv->hw);
@@ -7943,6 +7960,7 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	struct ieee80211_hw *hw;
 	struct iwl_3945_cfg *cfg = (struct iwl_3945_cfg *)(ent->driver_data);
 	int i;
+	unsigned long flags;
 	DECLARE_MAC_BUF(mac);
 
 	/* Disabling hardware scan means that mac80211 will perform scans
@@ -8093,7 +8111,9 @@ static int iwl3945_pci_probe(struct pci_dev *pdev, const struct pci_device_id *e
 	priv->power_mode = IWL_POWER_AC;
 	priv->user_txpower_limit = IWL_DEFAULT_TX_POWER;
 
+	spin_lock_irqsave(&priv->lock, flags);
 	iwl3945_disable_interrupts(priv);
+	spin_unlock_irqrestore(&priv->lock, flags);
 
 	err = sysfs_create_group(&pdev->dev.kobj, &iwl3945_attribute_group);
 	if (err) {
@@ -8180,6 +8200,7 @@ static void __devexit iwl3945_pci_remove(struct pci_dev *pdev)
 	struct iwl3945_priv *priv = pci_get_drvdata(pdev);
 	struct list_head *p, *q;
 	int i;
+	unsigned long flags;
 
 	if (!priv)
 		return;
@@ -8190,6 +8211,15 @@ static void __devexit iwl3945_pci_remove(struct pci_dev *pdev)
 
 	iwl3945_down(priv);
 
+	/* make sure we flush any pending irq or
+	 * tasklet for the driver
+	 */
+	spin_lock_irqsave(&priv->lock, flags);
+	iwl3945_disable_interrupts(priv);
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	iwl_synchronize_irq(priv);
+
 	/* Free MAC hash list for ADHOC */
 	for (i = 0; i < IWL_IBSS_MAC_HASH_SIZE; i++) {
 		list_for_each_safe(p, q, &priv->ibss_mac_hash[i]) {