[PATCH net v2] net: dlink: use dev_kfree_skb_any instead of dev_kfree_skb

[PATCH net v2] net: dlink: use dev_kfree_skb_any instead of dev_kfree_skb

[Yeounsu Moon]

Replace `dev_kfree_skb()` with `dev_kfree_skb_any()` in `start_xmit()`
which can be called from netpoll (hard IRQ) and from other contexts.

Also, `np->link_status` can be changed at any time by interrupt handler.

  <idle>-0       [011] dNh4.  4541.754603: start_xmit <-netpoll_start_xmit
  <idle>-0       [011] dNh4.  4541.754622: <stack trace>
 => [FTRACE TRAMPOLINE]
 => start_xmit
 => netpoll_start_xmit
 => netpoll_send_skb
 => write_msg
 => console_flush_all
 => console_unlock
 => vprintk_emit
 => _printk
 => rio_interrupt
 => __handle_irq_event_percpu
 => handle_irq_event
 => handle_fasteoi_irq
 => __common_interrupt
 => common_interrupt
 => asm_common_interrupt
 => mwait_idle
 => default_idle_call
 => do_idle
 => cpu_startup_entry
 => start_secondary
 => common_startup_64

This issue can occur when the link state changes from off to on
(e.g., plugging or unplugging the LAN cable) while transmitting a
packet. If the skb has a destructor, a warning message may be
printed in this situation.

-> consume_skb (dev_kfree_skb())
  -> __kfree_skb()
    -> skb_release_all()
      -> skb_release_head_state(skb)
	 if (skb->destructor) {
	         DEBUG_NET_WARN_ON_ONCE(in_hardirq());
		 skb->destructor(skb);
	 }

Found by inspection.

Signed-off-by: Yeounsu Moon <yyyynoom@gmail.com>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Tested-on: D-Link DGE-550T Rev-A3
Reviewed-by: Simon Horman <horms@kernel.org>
---
 drivers/net/ethernet/dlink/dl2k.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/dlink/dl2k.c b/drivers/net/ethernet/dlink/dl2k.c
index 7077d705e471..6e4f17142519 100644
--- a/drivers/net/ethernet/dlink/dl2k.c
+++ b/drivers/net/ethernet/dlink/dl2k.c
@@ -733,7 +733,7 @@ start_xmit (struct sk_buff *skb, struct net_device *dev)
 	u64 tfc_vlan_tag = 0;
 
 	if (np->link_status == 0) {	/* Link Down */
-		dev_kfree_skb(skb);
+		dev_kfree_skb_any(skb);
 		return NETDEV_TX_OK;
 	}
 	entry = np->cur_tx % TX_RING_SIZE;
-- 
2.51.0

Re: [PATCH net v2] net: dlink: use dev_kfree_skb_any instead of dev_kfree_skb

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Sun, 19 Oct 2025 16:55:40 +0900 you wrote:
> Replace `dev_kfree_skb()` with `dev_kfree_skb_any()` in `start_xmit()`
> which can be called from netpoll (hard IRQ) and from other contexts.
> 
> Also, `np->link_status` can be changed at any time by interrupt handler.
> 
>   <idle>-0       [011] dNh4.  4541.754603: start_xmit <-netpoll_start_xmit
>   <idle>-0       [011] dNh4.  4541.754622: <stack trace>
>  => [FTRACE TRAMPOLINE]
>  => start_xmit
>  => netpoll_start_xmit
>  => netpoll_send_skb
>  => write_msg
>  => console_flush_all
>  => console_unlock
>  => vprintk_emit
>  => _printk
>  => rio_interrupt
>  => __handle_irq_event_percpu
>  => handle_irq_event
>  => handle_fasteoi_irq
>  => __common_interrupt
>  => common_interrupt
>  => asm_common_interrupt
>  => mwait_idle
>  => default_idle_call
>  => do_idle
>  => cpu_startup_entry
>  => start_secondary
>  => common_startup_64
> 
> [...]

Here is the summary with links:
  - [net,v2] net: dlink: use dev_kfree_skb_any instead of dev_kfree_skb
    https://git.kernel.org/netdev/net/c/5523508258d3

You are awesome, thank you!
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