[PATCH v4] net: usb: Convert tasklet API to new bottom half workqueue mechanism

[PATCH v4] net: usb: Convert tasklet API to new bottom half workqueue mechanism

[Jun Miao]

Migrate tasklet APIs to the new bottom half workqueue mechanism. It
replaces all occurrences of tasklet usage with the appropriate workqueue
APIs throughout the usbnet driver. This transition ensures compatibility
with the latest design and enhances performance.

Signed-off-by: Jun Miao <jun.miao@intel.com>
---
v1->v2:
    Check patch warning, delete the more spaces.
v2->v3:
    Fix the kernel test robot noticed the following build errors:
    >> drivers/net/usb/usbnet.c:1974:47: error: 'struct usbnet' has no member named 'bh'
v3->v4:
	Keep "GFP_ATOMIC" flag as it is.
	If someone want to change the flags (which Im not sure is correct) it should be a separate commit.

---
 drivers/net/usb/usbnet.c   | 36 ++++++++++++++++++------------------
 include/linux/usb/usbnet.h |  2 +-
 2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index c04e715a4c2a..7d3791366509 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -461,7 +461,7 @@ static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,

 	__skb_queue_tail(&dev->done, skb);
 	if (dev->done.qlen == 1)
-		tasklet_schedule(&dev->bh);
+		queue_work(system_bh_wq, &dev->bh_work);
 	spin_unlock(&dev->done.lock);
 	spin_unlock_irqrestore(&list->lock, flags);
 	return old_state;
@@ -549,7 +549,7 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
 		default:
 			netif_dbg(dev, rx_err, dev->net,
 				  "rx submit, %d\n", retval);
-			tasklet_schedule (&dev->bh);
+			queue_work(system_bh_wq, &dev->bh_work);
 			break;
 		case 0:
 			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
@@ -709,7 +709,7 @@ void usbnet_resume_rx(struct usbnet *dev)
 		num++;
 	}

-	tasklet_schedule(&dev->bh);
+	queue_work(system_bh_wq, &dev->bh_work);

 	netif_dbg(dev, rx_status, dev->net,
 		  "paused rx queue disabled, %d skbs requeued\n", num);
@@ -778,7 +778,7 @@ void usbnet_unlink_rx_urbs(struct usbnet *dev)
 {
 	if (netif_running(dev->net)) {
 		(void) unlink_urbs (dev, &dev->rxq);
-		tasklet_schedule(&dev->bh);
+		queue_work(system_bh_wq, &dev->bh_work);
 	}
 }
 EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
@@ -861,14 +861,14 @@ int usbnet_stop (struct net_device *net)
 	/* deferred work (timer, softirq, task) must also stop */
 	dev->flags = 0;
 	timer_delete_sync(&dev->delay);
-	tasklet_kill(&dev->bh);
+	disable_work_sync(&dev->bh_work);
 	cancel_work_sync(&dev->kevent);

 	/* We have cyclic dependencies. Those calls are needed
 	 * to break a cycle. We cannot fall into the gaps because
 	 * we have a flag
 	 */
-	tasklet_kill(&dev->bh);
+	disable_work_sync(&dev->bh_work);
 	timer_delete_sync(&dev->delay);
 	cancel_work_sync(&dev->kevent);

@@ -955,7 +955,7 @@ int usbnet_open (struct net_device *net)
 	clear_bit(EVENT_RX_KILL, &dev->flags);

 	// delay posting reads until we're fully open
-	tasklet_schedule (&dev->bh);
+	queue_work(system_bh_wq, &dev->bh_work);
 	if (info->manage_power) {
 		retval = info->manage_power(dev, 1);
 		if (retval < 0) {
@@ -1123,7 +1123,7 @@ static void __handle_link_change(struct usbnet *dev)
 		 */
 	} else {
 		/* submitting URBs for reading packets */
-		tasklet_schedule(&dev->bh);
+		queue_work(system_bh_wq, &dev->bh_work);
 	}

 	/* hard_mtu or rx_urb_size may change during link change */
@@ -1198,11 +1198,11 @@ usbnet_deferred_kevent (struct work_struct *work)
 		} else {
 			clear_bit (EVENT_RX_HALT, &dev->flags);
 			if (!usbnet_going_away(dev))
-				tasklet_schedule(&dev->bh);
+				queue_work(system_bh_wq, &dev->bh_work);
 		}
 	}

-	/* tasklet could resubmit itself forever if memory is tight */
+	/* workqueue could resubmit itself forever if memory is tight */
 	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
 		struct urb	*urb = NULL;
 		int resched = 1;
@@ -1224,7 +1224,7 @@ usbnet_deferred_kevent (struct work_struct *work)
 fail_lowmem:
 			if (resched)
 				if (!usbnet_going_away(dev))
-					tasklet_schedule(&dev->bh);
+					queue_work(system_bh_wq, &dev->bh_work);
 		}
 	}

@@ -1325,7 +1325,7 @@ void usbnet_tx_timeout (struct net_device *net, unsigned int txqueue)
 	struct usbnet		*dev = netdev_priv(net);

 	unlink_urbs (dev, &dev->txq);
-	tasklet_schedule (&dev->bh);
+	queue_work(system_bh_wq, &dev->bh_work);
 	/* this needs to be handled individually because the generic layer
 	 * doesn't know what is sufficient and could not restore private
 	 * information if a remedy of an unconditional reset were used.
@@ -1547,7 +1547,7 @@ static inline void usb_free_skb(struct sk_buff *skb)

 /*-------------------------------------------------------------------------*/

-// tasklet (work deferred from completions, in_irq) or timer
+// workqueue (work deferred from completions, in_irq) or timer

 static void usbnet_bh (struct timer_list *t)
 {
@@ -1601,16 +1601,16 @@ static void usbnet_bh (struct timer_list *t)
 					  "rxqlen %d --> %d\n",
 					  temp, dev->rxq.qlen);
 			if (dev->rxq.qlen < RX_QLEN(dev))
-				tasklet_schedule (&dev->bh);
+				queue_work(system_bh_wq, &dev->bh_work);
 		}
 		if (dev->txq.qlen < TX_QLEN (dev))
 			netif_wake_queue (dev->net);
 	}
 }

-static void usbnet_bh_tasklet(struct tasklet_struct *t)
+static void usbnet_bh_workqueue(struct work_struct *work)
 {
-	struct usbnet *dev = from_tasklet(dev, t, bh);
+	struct usbnet *dev = from_work(dev, work, bh_work);

 	usbnet_bh(&dev->delay);
 }
@@ -1742,7 +1742,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	skb_queue_head_init (&dev->txq);
 	skb_queue_head_init (&dev->done);
 	skb_queue_head_init(&dev->rxq_pause);
-	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
+	INIT_WORK(&dev->bh_work, usbnet_bh_workqueue);
 	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
 	init_usb_anchor(&dev->deferred);
 	timer_setup(&dev->delay, usbnet_bh, 0);
@@ -1971,7 +1971,7 @@ int usbnet_resume (struct usb_interface *intf)

 			if (!(dev->txq.qlen >= TX_QLEN(dev)))
 				netif_tx_wake_all_queues(dev->net);
-			tasklet_schedule (&dev->bh);
+			queue_work(system_bh_wq, &dev->bh_work);
 		}
 	}

diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index 0b9f1e598e3a..208682f77179 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -58,7 +58,7 @@ struct usbnet {
 	unsigned		interrupt_count;
 	struct mutex		interrupt_mutex;
 	struct usb_anchor	deferred;
-	struct tasklet_struct	bh;
+	struct work_struct	bh_work;

 	struct work_struct	kevent;
 	unsigned long		flags;
--
2.27.0

Re: [PATCH v4] net: usb: Convert tasklet API to new bottom half workqueue mechanism

[Subbaraya Sundeep]

On 2025-06-15 at 01:53:15, Jun Miao (jun.miao@intel.com) wrote:
> Migrate tasklet APIs to the new bottom half workqueue mechanism. It
> replaces all occurrences of tasklet usage with the appropriate workqueue
> APIs throughout the usbnet driver. This transition ensures compatibility
> with the latest design and enhances performance.
> 
> Signed-off-by: Jun Miao <jun.miao@intel.com>

 Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>

 Thanks,
 Sundeep

> ---
> v1->v2:
>     Check patch warning, delete the more spaces.
> v2->v3:
>     Fix the kernel test robot noticed the following build errors:
>     >> drivers/net/usb/usbnet.c:1974:47: error: 'struct usbnet' has no member named 'bh'
> v3->v4:
> 	Keep "GFP_ATOMIC" flag as it is.
> 	If someone want to change the flags (which Im not sure is correct) it should be a separate commit.
> 
> ---
>  drivers/net/usb/usbnet.c   | 36 ++++++++++++++++++------------------
>  include/linux/usb/usbnet.h |  2 +-
>  2 files changed, 19 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
> index c04e715a4c2a..7d3791366509 100644
> --- a/drivers/net/usb/usbnet.c
> +++ b/drivers/net/usb/usbnet.c
> @@ -461,7 +461,7 @@ static enum skb_state defer_bh(struct usbnet *dev, struct sk_buff *skb,
> 
>  	__skb_queue_tail(&dev->done, skb);
>  	if (dev->done.qlen == 1)
> -		tasklet_schedule(&dev->bh);
> +		queue_work(system_bh_wq, &dev->bh_work);
>  	spin_unlock(&dev->done.lock);
>  	spin_unlock_irqrestore(&list->lock, flags);
>  	return old_state;
> @@ -549,7 +549,7 @@ static int rx_submit (struct usbnet *dev, struct urb *urb, gfp_t flags)
>  		default:
>  			netif_dbg(dev, rx_err, dev->net,
>  				  "rx submit, %d\n", retval);
> -			tasklet_schedule (&dev->bh);
> +			queue_work(system_bh_wq, &dev->bh_work);
>  			break;
>  		case 0:
>  			__usbnet_queue_skb(&dev->rxq, skb, rx_start);
> @@ -709,7 +709,7 @@ void usbnet_resume_rx(struct usbnet *dev)
>  		num++;
>  	}
> 
> -	tasklet_schedule(&dev->bh);
> +	queue_work(system_bh_wq, &dev->bh_work);
> 
>  	netif_dbg(dev, rx_status, dev->net,
>  		  "paused rx queue disabled, %d skbs requeued\n", num);
> @@ -778,7 +778,7 @@ void usbnet_unlink_rx_urbs(struct usbnet *dev)
>  {
>  	if (netif_running(dev->net)) {
>  		(void) unlink_urbs (dev, &dev->rxq);
> -		tasklet_schedule(&dev->bh);
> +		queue_work(system_bh_wq, &dev->bh_work);
>  	}
>  }
>  EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs);
> @@ -861,14 +861,14 @@ int usbnet_stop (struct net_device *net)
>  	/* deferred work (timer, softirq, task) must also stop */
>  	dev->flags = 0;
>  	timer_delete_sync(&dev->delay);
> -	tasklet_kill(&dev->bh);
> +	disable_work_sync(&dev->bh_work);
>  	cancel_work_sync(&dev->kevent);
> 
>  	/* We have cyclic dependencies. Those calls are needed
>  	 * to break a cycle. We cannot fall into the gaps because
>  	 * we have a flag
>  	 */
> -	tasklet_kill(&dev->bh);
> +	disable_work_sync(&dev->bh_work);
>  	timer_delete_sync(&dev->delay);
>  	cancel_work_sync(&dev->kevent);
> 
> @@ -955,7 +955,7 @@ int usbnet_open (struct net_device *net)
>  	clear_bit(EVENT_RX_KILL, &dev->flags);
> 
>  	// delay posting reads until we're fully open
> -	tasklet_schedule (&dev->bh);
> +	queue_work(system_bh_wq, &dev->bh_work);
>  	if (info->manage_power) {
>  		retval = info->manage_power(dev, 1);
>  		if (retval < 0) {
> @@ -1123,7 +1123,7 @@ static void __handle_link_change(struct usbnet *dev)
>  		 */
>  	} else {
>  		/* submitting URBs for reading packets */
> -		tasklet_schedule(&dev->bh);
> +		queue_work(system_bh_wq, &dev->bh_work);
>  	}
> 
>  	/* hard_mtu or rx_urb_size may change during link change */
> @@ -1198,11 +1198,11 @@ usbnet_deferred_kevent (struct work_struct *work)
>  		} else {
>  			clear_bit (EVENT_RX_HALT, &dev->flags);
>  			if (!usbnet_going_away(dev))
> -				tasklet_schedule(&dev->bh);
> +				queue_work(system_bh_wq, &dev->bh_work);
>  		}
>  	}
> 
> -	/* tasklet could resubmit itself forever if memory is tight */
> +	/* workqueue could resubmit itself forever if memory is tight */
>  	if (test_bit (EVENT_RX_MEMORY, &dev->flags)) {
>  		struct urb	*urb = NULL;
>  		int resched = 1;
> @@ -1224,7 +1224,7 @@ usbnet_deferred_kevent (struct work_struct *work)
>  fail_lowmem:
>  			if (resched)
>  				if (!usbnet_going_away(dev))
> -					tasklet_schedule(&dev->bh);
> +					queue_work(system_bh_wq, &dev->bh_work);
>  		}
>  	}
> 
> @@ -1325,7 +1325,7 @@ void usbnet_tx_timeout (struct net_device *net, unsigned int txqueue)
>  	struct usbnet		*dev = netdev_priv(net);
> 
>  	unlink_urbs (dev, &dev->txq);
> -	tasklet_schedule (&dev->bh);
> +	queue_work(system_bh_wq, &dev->bh_work);
>  	/* this needs to be handled individually because the generic layer
>  	 * doesn't know what is sufficient and could not restore private
>  	 * information if a remedy of an unconditional reset were used.
> @@ -1547,7 +1547,7 @@ static inline void usb_free_skb(struct sk_buff *skb)
> 
>  /*-------------------------------------------------------------------------*/
> 
> -// tasklet (work deferred from completions, in_irq) or timer
> +// workqueue (work deferred from completions, in_irq) or timer
> 
>  static void usbnet_bh (struct timer_list *t)
>  {
> @@ -1601,16 +1601,16 @@ static void usbnet_bh (struct timer_list *t)
>  					  "rxqlen %d --> %d\n",
>  					  temp, dev->rxq.qlen);
>  			if (dev->rxq.qlen < RX_QLEN(dev))
> -				tasklet_schedule (&dev->bh);
> +				queue_work(system_bh_wq, &dev->bh_work);
>  		}
>  		if (dev->txq.qlen < TX_QLEN (dev))
>  			netif_wake_queue (dev->net);
>  	}
>  }
> 
> -static void usbnet_bh_tasklet(struct tasklet_struct *t)
> +static void usbnet_bh_workqueue(struct work_struct *work)
>  {
> -	struct usbnet *dev = from_tasklet(dev, t, bh);
> +	struct usbnet *dev = from_work(dev, work, bh_work);
> 
>  	usbnet_bh(&dev->delay);
>  }
> @@ -1742,7 +1742,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
>  	skb_queue_head_init (&dev->txq);
>  	skb_queue_head_init (&dev->done);
>  	skb_queue_head_init(&dev->rxq_pause);
> -	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
> +	INIT_WORK(&dev->bh_work, usbnet_bh_workqueue);
>  	INIT_WORK (&dev->kevent, usbnet_deferred_kevent);
>  	init_usb_anchor(&dev->deferred);
>  	timer_setup(&dev->delay, usbnet_bh, 0);
> @@ -1971,7 +1971,7 @@ int usbnet_resume (struct usb_interface *intf)
> 
>  			if (!(dev->txq.qlen >= TX_QLEN(dev)))
>  				netif_tx_wake_all_queues(dev->net);
> -			tasklet_schedule (&dev->bh);
> +			queue_work(system_bh_wq, &dev->bh_work);
>  		}
>  	}
> 
> diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
> index 0b9f1e598e3a..208682f77179 100644
> --- a/include/linux/usb/usbnet.h
> +++ b/include/linux/usb/usbnet.h
> @@ -58,7 +58,7 @@ struct usbnet {
>  	unsigned		interrupt_count;
>  	struct mutex		interrupt_mutex;
>  	struct usb_anchor	deferred;
> -	struct tasklet_struct	bh;
> +	struct work_struct	bh_work;
> 
>  	struct work_struct	kevent;
>  	unsigned long		flags;
> --
> 2.27.0
> 

Re: [PATCH v4] net: usb: Convert tasklet API to new bottom half workqueue mechanism

[Jakub Kicinski]

On Sun, 15 Jun 2025 09:53:15 +0800 Jun Miao wrote:
> -static void usbnet_bh_tasklet(struct tasklet_struct *t)
> +static void usbnet_bh_workqueue(struct work_struct *work)
>  {
> -	struct usbnet *dev = from_tasklet(dev, t, bh);
> +	struct usbnet *dev = from_work(dev, work, bh_work);
> 
>  	usbnet_bh(&dev->delay);
>  }
> @@ -1742,7 +1742,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
>  	skb_queue_head_init (&dev->txq);
>  	skb_queue_head_init (&dev->done);
>  	skb_queue_head_init(&dev->rxq_pause);
> -	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
> +	INIT_WORK(&dev->bh_work, usbnet_bh_workqueue);

workqueue is the queue, here we're talking about the work entry.
And we use the system workqueue to schedule on (system_bh_wq)
Please replace the workqueue with work here and in the comments

RE: [PATCH v4] net: usb: Convert tasklet API to new bottom half workqueue mechanism

[Miao, Jun]

>
>On Sun, 15 Jun 2025 09:53:15 +0800 Jun Miao wrote:
>> -static void usbnet_bh_tasklet(struct tasklet_struct *t)
>> +static void usbnet_bh_workqueue(struct work_struct *work)
>>  {
>> -	struct usbnet *dev = from_tasklet(dev, t, bh);
>> +	struct usbnet *dev = from_work(dev, work, bh_work);
>>
>>  	usbnet_bh(&dev->delay);
>>  }
>> @@ -1742,7 +1742,7 @@ usbnet_probe (struct usb_interface *udev, const
>struct usb_device_id *prod)
>>  	skb_queue_head_init (&dev->txq);
>>  	skb_queue_head_init (&dev->done);
>>  	skb_queue_head_init(&dev->rxq_pause);
>> -	tasklet_setup(&dev->bh, usbnet_bh_tasklet);
>> +	INIT_WORK(&dev->bh_work, usbnet_bh_workqueue);
>
>workqueue is the queue, here we're talking about the work entry.
>And we use the system workqueue to schedule on (system_bh_wq) Please replace
>the workqueue with work here and in the comments

Oh, I understand what you mean. The naming is not accurate enough. 
This is not a queue but a specific execution action work.  V5 will post. 

Thanks
Jun.Miao