[PATCH 2/5] iwlwifi: iwl3945 synchronize interrupt and tasklet for down iwlwifi

[PATCH 2/5] iwlwifi: iwl3945 synchronize interrupt and tasklet for down iwlwifi

[Joonwoo Park]

After disabling interrupts, it's possible irq & tasklet is pending or running
This patch eleminates races for down iwlwifi

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
---
 drivers/net/wireless/iwlwifi/iwl3945-base.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index c97448d..3986aaf 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -6262,6 +6262,10 @@ static void __iwl_down(struct iwl_priv *priv)
 	/* tell the device to stop sending interrupts */
 	iwl_disable_interrupts(priv);
 
+	/* synchronize irq and tasklet */
+	synchronize_irq(priv->pci_dev->irq);
+	tasklet_kill(&priv->irq_tasklet);
+
 	if (priv->mac80211_registered)
 		ieee80211_stop_queues(priv->hw);
 
-- 
1.5.3.rc5

RE: [ipw3945-devel] [PATCH 2/5] iwlwifi: iwl3945 synchronize interruptand tasklet for down iwlwifi

[Chatre, Reinette]

On , Joonwoo Park  wrote:

> --- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
> +++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
> @@ -6262,6 +6262,10 @@ static void __iwl_down(struct iwl_priv *priv)
> 	/* tell the device to stop sending interrupts */
> 	iwl_disable_interrupts(priv);
> 
> +	/* synchronize irq and tasklet */
> +	synchronize_irq(priv->pci_dev->irq);
> +	tasklet_kill(&priv->irq_tasklet);
> +

Could synchronize_irq() be moved into iwl_disable_interrupts() ? I am
also wondering if we cannot call tasklet_kill() before
iwl_disable_interrupts() ... thus preventing it from being scheduled
when we are going down. 

Reinette

Re: [ipw3945-devel] [PATCH 2/5] iwlwifi: iwl3945 synchronize interruptand tasklet for down iwlwifi

[Joonwoo Park]

Hello Reinette,

2008/1/11, Chatre, Reinette <reinette.chatre@intel.com>:
>
> Could synchronize_irq() be moved into iwl_disable_interrupts() ? I am

At this time, iwl_disable_interrupts() can be called with irq
disabled, so for do that I think additional modification would be
needed.

> also wondering if we cannot call tasklet_kill() before
> iwl_disable_interrupts() ... thus preventing it from being scheduled
> when we are going down.

Thanks for your catch, it seems tasklet can re-enable interrupts.
I'll handle and make an another patch for them at this weekend :)

Thanks,
Joonwoo

Re: [ipw3945-devel] [PATCH 2/5] iwlwifi: iwl3945 synchronize interruptand tasklet for down iwlwifi

[Joonwoo Park]

Joonwoo Park wrote:
> 2008/1/11, Chatre, Reinette <reinette.chatre@intel.com>:
>> On Thursday, January 10, 2008 5:25 PM, Joonwoo Park  wrote:
> 
>> What modification are you considering?
> 
> Roughly, I'm considering make synchronize_irq() be moved into
> iwl_disable_interrupts() and fix iwl_irq_tasket not to call
> iwl_disable_interrupts with irq disabled.
> For now iwl_irq_tasklet calls iwl_disable_interrupts() with local irq disabled.
> like this:
> 
> static void iwl_irq_tasklet(struct iwl_priv *priv)
> {
>         ...
>         spin_lock_irqsave(&priv->lock, flags);
> 
>         ...
>         /* Now service all interrupt bits discovered above. */
>         if (inta & CSR_INT_BIT_HW_ERR) {
>                 IWL_ERROR("Microcode HW error detected.  Restarting.\n");
> 
>                 /* Tell the device to stop sending interrupts */
>                 iwl_disable_interrupts(priv);
>                 ...
>                 spin_unlock_irqrestore(&priv->lock, flags);
>                 return;
>         }
> 
> 

After disabling interrupts, it's possible irq & tasklet is pending or running
This patch eleminates races for down iwlwifi

Since synchronize_irq can introduce iwl_irq_tasklet, tasklet_kill
should be called after doing synchronize_irq
To avoid races between iwl_synchronize_irq and iwl_irq_tasklet STATUS_INT_ENABLED
flag is needed.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
---
   drivers/net/wireless/iwlwifi/iwl3945-base.c |   33 ++++++++++++++++++++++-----
   1 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index 6e20725..f98cd4f 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -4405,6 +4405,14 @@ static void iwl_print_rx_config_cmd(struct iwl_rxon_cmd *rxon)
   }
   #endif

+static void iwl_synchronize_interrupts(struct iwl_priv *priv)
+{
+	synchronize_irq(priv->pci_dev->irq);
+	/* synchornize_irq introduces irq_tasklet,
+	 * tasklet_kill should be called after doing synchronize_irq */
+	tasklet_kill(&priv->irq_tasklet);
+}
+
   static void iwl_enable_interrupts(struct iwl_priv *priv)
   {
   	IWL_DEBUG_ISR("Enabling interrupts\n");
@@ -4413,7 +4421,7 @@ static void iwl_enable_interrupts(struct iwl_priv *priv)
   	iwl_flush32(priv, CSR_INT_MASK);
   }

-static inline void iwl_disable_interrupts(struct iwl_priv *priv)
+static inline void __iwl_disable_interrupts(struct iwl_priv *priv)
   {
   	clear_bit(STATUS_INT_ENABLED, &priv->status);

@@ -4427,6 +4435,13 @@ static inline void iwl_disable_interrupts(struct iwl_priv *priv)
   	iwl_flush32(priv, CSR_INT);
   	iwl_write32(priv, CSR_FH_INT_STATUS, 0xffffffff);
   	iwl_flush32(priv, CSR_FH_INT_STATUS);
+}
+
+static inline void iwl_disable_interrupts(struct iwl_priv *priv)
+{
+	__iwl_disable_interrupts(priv);
+
+	iwl_synchronize_interrupts(priv);

   	IWL_DEBUG_ISR("Disabled interrupts\n");
   }
@@ -4708,7 +4723,8 @@ static void iwl_irq_tasklet(struct iwl_priv *priv)
   		IWL_ERROR("Microcode HW error detected.  Restarting.\n");

   		/* Tell the device to stop sending interrupts */
-		iwl_disable_interrupts(priv);
+		__iwl_disable_interrupts(priv);
+		IWL_DEBUG_ISR("Disabled interrupts\n");

   		iwl_irq_handle_error(priv);

@@ -4814,8 +4830,11 @@ static void iwl_irq_tasklet(struct iwl_priv *priv)
   		IWL_WARNING("   with FH_INT = 0x%08x\n", inta_fh);
   	}

-	/* Re-enable all interrupts */
-	iwl_enable_interrupts(priv);
+	/* To avoid race when device goes down,
+	 * it should be discarded to enable interrupts */
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		/* Re-enable all interrupts */
+		iwl_enable_interrupts(priv);

   #ifdef CONFIG_IWLWIFI_DEBUG
   	if (iwl_debug_level & (IWL_DL_ISR)) {
@@ -4876,8 +4895,10 @@ unplugged:
   	return IRQ_HANDLED;

    none:
-	/* re-enable interrupts here since we don't have anything to service. */
-	iwl_enable_interrupts(priv);
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		/* re-enable interrupts here since we don't have anything
+		 * to service. */
+		iwl_enable_interrupts(priv);
   	spin_unlock(&priv->lock);
   	return IRQ_NONE;
   }
---

Thanks,
Joonwoo

Re: [ipw3945-devel] [PATCH 2/5] iwlwifi: iwl3945 synchronize interruptand tasklet for down iwlwifi

[Joonwoo Park]

I'm so sorry for mangled patch.
resending patch with preformat html from thunderbird.


After disabling interrupts, it's possible irq & tasklet is pending or running
This patch eleminates races for down iwlwifi.

Since synchronize_irq can introduce iwl_irq_tasklet, tasklet_kill should be 
called after doing synchronize_irq.
To avoid races between iwl_synchronize_irq and iwl_irq_tasklet
STATUS_INT_ENABLED flag is needed.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
---
 drivers/net/wireless/iwlwifi/iwl3945-base.c |   33 ++++++++++++++++++++++-----
 1 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl3945-base.c b/drivers/net/wireless/iwlwifi/iwl3945-base.c
index 6e20725..f98cd4f 100644
--- a/drivers/net/wireless/iwlwifi/iwl3945-base.c
+++ b/drivers/net/wireless/iwlwifi/iwl3945-base.c
@@ -4405,6 +4405,14 @@ static void iwl_print_rx_config_cmd(struct iwl_rxon_cmd *rxon)
 }
 #endif
 
+static void iwl_synchronize_interrupts(struct iwl_priv *priv)
+{
+	synchronize_irq(priv->pci_dev->irq);
+	/* synchornize_irq introduces irq_tasklet,
+	 * tasklet_kill should be called after doing synchronize_irq */
+	tasklet_kill(&priv->irq_tasklet);
+}
+
 static void iwl_enable_interrupts(struct iwl_priv *priv)
 {
 	IWL_DEBUG_ISR("Enabling interrupts\n");
@@ -4413,7 +4421,7 @@ static void iwl_enable_interrupts(struct iwl_priv *priv)
 	iwl_flush32(priv, CSR_INT_MASK);
 }
 
-static inline void iwl_disable_interrupts(struct iwl_priv *priv)
+static inline void __iwl_disable_interrupts(struct iwl_priv *priv)
 {
 	clear_bit(STATUS_INT_ENABLED, &priv->status);
 
@@ -4427,6 +4435,13 @@ static inline void iwl_disable_interrupts(struct iwl_priv *priv)
 	iwl_flush32(priv, CSR_INT);
 	iwl_write32(priv, CSR_FH_INT_STATUS, 0xffffffff);
 	iwl_flush32(priv, CSR_FH_INT_STATUS);
+}
+
+static inline void iwl_disable_interrupts(struct iwl_priv *priv)
+{
+	__iwl_disable_interrupts(priv);
+
+	iwl_synchronize_interrupts(priv);
 
 	IWL_DEBUG_ISR("Disabled interrupts\n");
 }
@@ -4708,7 +4723,8 @@ static void iwl_irq_tasklet(struct iwl_priv *priv)
 		IWL_ERROR("Microcode HW error detected.  Restarting.\n");
 
 		/* Tell the device to stop sending interrupts */
-		iwl_disable_interrupts(priv);
+		__iwl_disable_interrupts(priv);
+		IWL_DEBUG_ISR("Disabled interrupts\n");
 
 		iwl_irq_handle_error(priv);
 
@@ -4814,8 +4830,11 @@ static void iwl_irq_tasklet(struct iwl_priv *priv)
 		IWL_WARNING("   with FH_INT = 0x%08x\n", inta_fh);
 	}
 
-	/* Re-enable all interrupts */
-	iwl_enable_interrupts(priv);
+	/* To avoid race when device goes down,
+	 * it should be discarded to enable interrupts */
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		/* Re-enable all interrupts */
+		iwl_enable_interrupts(priv);
 
 #ifdef CONFIG_IWLWIFI_DEBUG
 	if (iwl_debug_level & (IWL_DL_ISR)) {
@@ -4876,8 +4895,10 @@ unplugged:
 	return IRQ_HANDLED;
 
  none:
-	/* re-enable interrupts here since we don't have anything to service. */
-	iwl_enable_interrupts(priv);
+	if (test_bit(STATUS_INT_ENABLED, &priv->status))
+		/* re-enable interrupts here since we don't have anything
+		 * to service. */
+		iwl_enable_interrupts(priv);
 	spin_unlock(&priv->lock);
 	return IRQ_NONE;
 }
---

Thanks,
Joonwoo