Commit cbe08724 authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: flush_backlog() small changes 



Add READ_ONCE() around reads of skb->dev->reg_state, because
this field can be changed from other threads/cpus.

Instead of calling dev_kfree_skb_irq() and kfree_skb()
while interrupts are masked and locks held,
use a temporary list and use __skb_queue_purge_reason()

Use SKB_DROP_REASON_DEV_READY drop reason to better
describe why these skbs are dropped.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Reviewed-by: default avatarJason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20250204144825.316785-1-edumazet@google.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 6cccb3bb

net/core/dev.c

+8 −4
Original line number Diff line number Diff line
@@ -6119,16 +6119,18 @@ EXPORT_SYMBOL(netif_receive_skb_list); 
static void flush_backlog(struct work_struct *work)

{

	struct sk_buff *skb, *tmp;

	struct sk_buff_head list;

	struct softnet_data *sd;



	__skb_queue_head_init(&list);

	local_bh_disable();

	sd = this_cpu_ptr(&softnet_data);



	backlog_lock_irq_disable(sd);

	skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {

		if (skb->dev->reg_state == NETREG_UNREGISTERING) {

		if (READ_ONCE(skb->dev->reg_state) == NETREG_UNREGISTERING) {

			__skb_unlink(skb, &sd->input_pkt_queue);

			dev_kfree_skb_irq(skb);

			__skb_queue_tail(&list, skb);

			rps_input_queue_head_incr(sd);

		}

	}
@@ -6136,14 +6138,16 @@ static void flush_backlog(struct work_struct *work) 


	local_lock_nested_bh(&softnet_data.process_queue_bh_lock);

	skb_queue_walk_safe(&sd->process_queue, skb, tmp) {

		if (skb->dev->reg_state == NETREG_UNREGISTERING) {

		if (READ_ONCE(skb->dev->reg_state) == NETREG_UNREGISTERING) {

			__skb_unlink(skb, &sd->process_queue);

			kfree_skb(skb);

			__skb_queue_tail(&list, skb);

			rps_input_queue_head_incr(sd);

		}

	}

	local_unlock_nested_bh(&softnet_data.process_queue_bh_lock);

	local_bh_enable();



	__skb_queue_purge_reason(&list, SKB_DROP_REASON_DEV_READY);

}



static bool flush_required(int cpu)