On Tue, 2007-12-18 at 15:57 +0100, Johannes Berg wrote:
> Thanks. This is a bug in iwlwifi.
>
> The problem is actually another case where my workqueue debugging with
> lockdep is triggering a warning :))
>
> Here's the thing:
>
> iwl3945_cancel_deferred_work does
>
> cancel_delayed_work_sync(&priv->init_alive_start);
>
> (which is the "(&(&priv->init_alive_start)->work)" lock)
>
> but it is called from within a locked section of
> mutex_lock(&priv->mutex); (locked from iwl3945_pci_suspend)
>
> On the other hand, the task that runs from the init_alive_start
> workqueue is iwl3945_bg_init_alive_start() which will lock the same
> mutex.
>
> So the deadlock condition is that you can be in
> cancel_delayed_work_sync() above while the mutex is locked, and be
> waiting for iwl_3945_bg_init_alive_start() which tries to lock the
> mutex.
Thanks for the analysis.
Miles, please try the attached patch. I'll send a patch for both 3945
and 4965 to linux-wireless later.
Thanks,
-yi
diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index 88cf035..f0303e8 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -6355,8 +6355,6 @@ static void __iwl3945_down(struct iwl3945_priv *priv)
/* Unblock any waiting calls */
wake_up_interruptible_all(&priv->wait_command_queue);
- iwl3945_cancel_deferred_work(priv);
-
/* Wipe out the EXIT_PENDING status bit if we are not actually
* exiting the module */
if (!exit_pending)
@@ -6431,6 +6429,8 @@ static void iwl3945_down(struct iwl3945_priv *priv)
mutex_lock(&priv->mutex);
__iwl3945_down(priv);
mutex_unlock(&priv->mutex);
+
+ iwl3945_cancel_deferred_work(priv);
}
#define MAX_HW_RESTARTS 5
@@ -8739,10 +8739,9 @@ static void iwl3945_pci_remove(struct pci_dev *pdev)
IWL_DEBUG_INFO("*** UNLOAD DRIVER ***\n");
- mutex_lock(&priv->mutex);
set_bit(STATUS_EXIT_PENDING, &priv->status);
- __iwl3945_down(priv);
- mutex_unlock(&priv->mutex);
+
+ iwl3945_down(priv);
/* Free MAC hash list for ADHOC */
for (i = 0; i < IWL_IBSS_MAC_HASH_SIZE; i++) {
@@ -8801,12 +8800,10 @@ static int iwl3945_pci_suspend(struct pci_dev *pdev, pm_message_t state)
{
struct iwl3945_priv *priv = pci_get_drvdata(pdev);
- mutex_lock(&priv->mutex);
-
set_bit(STATUS_IN_SUSPEND, &priv->status);
/* Take down the device; powers it off, etc. */
- __iwl3945_down(priv);
+ iwl3945_down(priv);
if (priv->mac80211_registered)
ieee80211_stop_queues(priv->hw);
@@ -8815,8 +8812,6 @@ static int iwl3945_pci_suspend(struct pci_dev *pdev, pm_message_t state)
pci_disable_device(pdev);
pci_set_power_state(pdev, PCI_D3hot);
- mutex_unlock(&priv->mutex);
-
return 0;
}
@@ -8874,8 +8869,6 @@ static int iwl3945_pci_resume(struct pci_dev *pdev)
printk(KERN_INFO "Coming out of suspend...\n");
- mutex_lock(&priv->mutex);
-
pci_set_power_state(pdev, PCI_D0);
err = pci_enable_device(pdev);
pci_restore_state(pdev);
@@ -8889,7 +8882,6 @@ static int iwl3945_pci_resume(struct pci_dev *pdev)
pci_write_config_byte(pdev, 0x41, 0x00);
iwl3945_resume(priv);
- mutex_unlock(&priv->mutex);
return 0;
}
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