Since 0417adf367a0 ("ppp: fix race conditions in ppp_fill_forward_path")
dev_fill_forward_path() should be called with RCU read lock held. This
fix was applied to net, while the Airoha flowtable commit was applied to
net-next, so it hadn't been an issue until net was merged into net-next.

Fixes: a9af709fda7e ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
Signed-off-by: Qingfang Deng <dqfext@gmail.com>
---
 drivers/net/ethernet/airoha/airoha_ppe.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
index ec5ce41dad80..02deb739a1c7 100644
--- a/drivers/net/ethernet/airoha/airoha_ppe.c
+++ b/drivers/net/ethernet/airoha/airoha_ppe.c
@@ -227,7 +227,9 @@ static int airoha_ppe_get_wdma_info(struct net_device *dev, const u8 *addr,
 	if (!dev)
 		return -ENODEV;
 
+	rcu_read_lock();
 	err = dev_fill_forward_path(dev, addr, &stack);
+	rcu_read_unlock();
 	if (err)
 		return err;
 
-- 
2.43.0

On Thu, Mar 19, 2026 at 11:26:49AM +0800, Qingfang Deng wrote:
> Since 0417adf367a0 ("ppp: fix race conditions in ppp_fill_forward_path")
> dev_fill_forward_path() should be called with RCU read lock held. This
> fix was applied to net, while the Airoha flowtable commit was applied to
> net-next, so it hadn't been an issue until net was merged into net-next.
> 
> Fixes: a9af709fda7e ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
> Signed-off-by: Qingfang Deng <dqfext@gmail.com>

I understand from the patch description that the problem didn't manifest
until this merge commit. But nonetheless I don't think using
a merge commit in the Fixes tag is the best approach. For one thing,
it seems somewhat difficult to use effectively to guide backporting.

I would suggest using the flowtable commit as the fixes tag:

Fixes: a8bdd935d1dd ("net: airoha: Add wlan flowtable TX offload")

Or perhaps fixes tags for both a8bdd935d1dd and 0417adf367a0.

Flagged by AI generated code review, which also suggested citing a8bdd935d1dd.


...

On Fri, Mar 20, 2026 at 5:19 PM Simon Horman <horms@kernel.org> wrote:
> I understand from the patch description that the problem didn't manifest
> until this merge commit. But nonetheless I don't think using
> a merge commit in the Fixes tag is the best approach. For one thing,
> it seems somewhat difficult to use effectively to guide backporting.
>
> I would suggest using the flowtable commit as the fixes tag:
>
> Fixes: a8bdd935d1dd ("net: airoha: Add wlan flowtable TX offload")
>
> Or perhaps fixes tags for both a8bdd935d1dd and 0417adf367a0.
>
> Flagged by AI generated code review, which also suggested citing a8bdd935d1dd.

Okay, I'll update the tag in v2.

> Since 0417adf367a0 ("ppp: fix race conditions in ppp_fill_forward_path")
> dev_fill_forward_path() should be called with RCU read lock held. This
> fix was applied to net, while the Airoha flowtable commit was applied to
> net-next, so it hadn't been an issue until net was merged into net-next.
> 
> Fixes: a9af709fda7e ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
> Signed-off-by: Qingfang Deng <dqfext@gmail.com>

Acked-by: Lorenzo Bianconi <lorenzo@kernel.org>

> ---
>  drivers/net/ethernet/airoha/airoha_ppe.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
> index ec5ce41dad80..02deb739a1c7 100644
> --- a/drivers/net/ethernet/airoha/airoha_ppe.c
> +++ b/drivers/net/ethernet/airoha/airoha_ppe.c
> @@ -227,7 +227,9 @@ static int airoha_ppe_get_wdma_info(struct net_device *dev, const u8 *addr,
>  	if (!dev)
>  		return -ENODEV;
>  
> +	rcu_read_lock();
>  	err = dev_fill_forward_path(dev, addr, &stack);
> +	rcu_read_unlock();
>  	if (err)
>  		return err;
>  
> -- 
> 2.43.0
>