[PATCH net] net: ethernet: mtk_eth_soc: Reset prog ptr to NULL in case of error in mtk_xdp_setup()

[PATCH net] net: ethernet: mtk_eth_soc: Reset prog ptr to NULL in case of error in mtk_xdp_setup()

[Lorenzo Bianconi]

Reset eBPF prog pointer to NULL if mtk_open routine in mtk_xdp_setup()
fails.

Fixes: 7c26c20da5d42 ("net: ethernet: mtk_eth_soc: add basic XDP support")
Suggested-by: Paolo Valerio <pvalerio@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
 drivers/net/ethernet/mediatek/mtk_eth_soc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index e5e2ffa9c542bfc88dc0d7553d0a6b2a169ec74b..e199f2e243d21f3545e8282ab821135e0962f5c3 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -3751,8 +3751,16 @@ static int mtk_xdp_setup(struct net_device *dev, struct bpf_prog *prog,
 	if (old_prog)
 		bpf_prog_put(old_prog);
 
-	if (netif_running(dev) && need_update)
-		return mtk_open(dev);
+	if (netif_running(dev) && need_update) {
+		int err;
+
+		err = mtk_open(dev);
+		if (err) {
+			rcu_assign_pointer(eth->prog, NULL);
+
+			return err;
+		}
+	}
 
 	return 0;
 }

---
base-commit: fd6dad4e1ae296b67b87291256878a58dad36c93
change-id: 20260227-mtk-xdp-prog-ptr-fix-af59b9cce7ba

Best regards,
-- 
Lorenzo Bianconi <lorenzo@kernel.org>

Re: [PATCH net] net: ethernet: mtk_eth_soc: Reset prog ptr to NULL in case of error in mtk_xdp_setup()

[Simon Horman]

On Fri, Feb 27, 2026 at 04:52:11PM +0100, Lorenzo Bianconi wrote:
> Reset eBPF prog pointer to NULL if mtk_open routine in mtk_xdp_setup()
> fails.
> 
> Fixes: 7c26c20da5d42 ("net: ethernet: mtk_eth_soc: add basic XDP support")
> Suggested-by: Paolo Valerio <pvalerio@redhat.com>
> Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>

Reviewed-by: Simon Horman <horms@kernel.org>

...

Re: [PATCH net] net: ethernet: mtk_eth_soc: Reset prog ptr to NULL in case of error in mtk_xdp_setup()

[Jakub Kicinski]

On Fri, 27 Feb 2026 16:52:11 +0100 Lorenzo Bianconi wrote:
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -3751,8 +3751,16 @@ static int mtk_xdp_setup(struct net_device *dev, struct bpf_prog *prog,
>  	if (old_prog)
>  		bpf_prog_put(old_prog);
>  
> -	if (netif_running(dev) && need_update)
> -		return mtk_open(dev);
> +	if (netif_running(dev) && need_update) {
> +		int err;
> +
> +		err = mtk_open(dev);
> +		if (err) {
> +			rcu_assign_pointer(eth->prog, NULL);
> +
> +			return err;
> +		}
> +	}
>  
>  	return 0;

Maybe there's something special here, not obvious without context,
but why are we setting eth->prog to NULL rather than old_prog?
At the very least the commit message needs to explain..
-- 
pw-bot: cr

Re: [PATCH net] net: ethernet: mtk_eth_soc: Reset prog ptr to NULL in case of error in mtk_xdp_setup()

[Lorenzo Bianconi]

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> On Fri, 27 Feb 2026 16:52:11 +0100 Lorenzo Bianconi wrote:
> > --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> > @@ -3751,8 +3751,16 @@ static int mtk_xdp_setup(struct net_device *dev, struct bpf_prog *prog,
> >  	if (old_prog)
> >  		bpf_prog_put(old_prog);
> >  
> > -	if (netif_running(dev) && need_update)
> > -		return mtk_open(dev);
> > +	if (netif_running(dev) && need_update) {
> > +		int err;
> > +
> > +		err = mtk_open(dev);
> > +		if (err) {
> > +			rcu_assign_pointer(eth->prog, NULL);
> > +
> > +			return err;
> > +		}
> > +	}
> >  
> >  	return 0;
> 
> Maybe there's something special here, not obvious without context,
> but why are we setting eth->prog to NULL rather than old_prog?
> At the very least the commit message needs to explain..

Reviewing the code I agree, we can just restore the old program, moving
bpf_prog_put() below the error condition. I will fix it in v2.

Regards,
Lorenzo

> -- 
> pw-bot: cr

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