In mtk_star_rx_poll function, on event processing completion, the
mtk_star_emac driver calls napi_complete_done but ignores its return
code and enable RX DMA interrupts inconditionally. This return code
gives the info if a device should avoid rearming its interrupts or not,
so fix this behaviour by taking it into account.

Fixes: 8c7bd5a454ff ("net: ethernet: mtk-star-emac: new driver")
Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
---
 drivers/net/ethernet/mediatek/mtk_star_emac.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_star_emac.c b/drivers/net/ethernet/mediatek/mtk_star_emac.c
index 23115881d8e892a622b34b593cf38e2c8bed4082..b175119a6a7da517f20267fde7b2005d6c0bbadd 100644
--- a/drivers/net/ethernet/mediatek/mtk_star_emac.c
+++ b/drivers/net/ethernet/mediatek/mtk_star_emac.c
@@ -1348,8 +1348,7 @@ static int mtk_star_rx_poll(struct napi_struct *napi, int budget)
 	priv = container_of(napi, struct mtk_star_priv, rx_napi);
 
 	work_done = mtk_star_rx(priv, budget);
-	if (work_done < budget) {
-		napi_complete_done(napi, work_done);
+	if (work_done < budget && napi_complete_done(napi, work_done)) {
 		spin_lock_irqsave(&priv->lock, flags);
 		mtk_star_enable_dma_irq(priv, true, false);
 		spin_unlock_irqrestore(&priv->lock, flags);

-- 
2.49.0

On Thu, Apr 24, 2025 at 10:40 AM Louis-Alexis Eyraud
<louisalexis.eyraud@collabora.com> wrote:
>
> In mtk_star_rx_poll function, on event processing completion, the
> mtk_star_emac driver calls napi_complete_done but ignores its return
> code and enable RX DMA interrupts inconditionally. This return code
> gives the info if a device should avoid rearming its interrupts or not,
> so fix this behaviour by taking it into account.
>
> Fixes: 8c7bd5a454ff ("net: ethernet: mtk-star-emac: new driver")
> Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
> ---
>  drivers/net/ethernet/mediatek/mtk_star_emac.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_star_emac.c b/drivers/net/ethernet/mediatek/mtk_star_emac.c
> index 23115881d8e892a622b34b593cf38e2c8bed4082..b175119a6a7da517f20267fde7b2005d6c0bbadd 100644
> --- a/drivers/net/ethernet/mediatek/mtk_star_emac.c
> +++ b/drivers/net/ethernet/mediatek/mtk_star_emac.c
> @@ -1348,8 +1348,7 @@ static int mtk_star_rx_poll(struct napi_struct *napi, int budget)
>         priv = container_of(napi, struct mtk_star_priv, rx_napi);
>
>         work_done = mtk_star_rx(priv, budget);
> -       if (work_done < budget) {
> -               napi_complete_done(napi, work_done);
> +       if (work_done < budget && napi_complete_done(napi, work_done)) {
>                 spin_lock_irqsave(&priv->lock, flags);
>                 mtk_star_enable_dma_irq(priv, true, false);
>                 spin_unlock_irqrestore(&priv->lock, flags);
>
> --
> 2.49.0
>

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Hi,

On Thu, 24 Apr 2025 10:38:49 +0200
Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com> wrote:

> In mtk_star_rx_poll function, on event processing completion, the
> mtk_star_emac driver calls napi_complete_done but ignores its return
> code and enable RX DMA interrupts inconditionally. This return code
> gives the info if a device should avoid rearming its interrupts or not,
> so fix this behaviour by taking it into account.
> 
> Fixes: 8c7bd5a454ff ("net: ethernet: mtk-star-emac: new driver")
> Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>

I'm unsure wether this counts as a bugfix, as no bug was
seen, and there are quite a few divers that already ignore the return
from napi_complete_done().

I don't think the patch is wrong, but maybe it should be sent to
net-next :/

Maxime

On Thu, 24 Apr 2025 11:16:23 +0200 Maxime Chevallier wrote:
> > In mtk_star_rx_poll function, on event processing completion, the
> > mtk_star_emac driver calls napi_complete_done but ignores its return
> > code and enable RX DMA interrupts inconditionally. This return code
> > gives the info if a device should avoid rearming its interrupts or not,
> > so fix this behaviour by taking it into account.
> > 
> > Fixes: 8c7bd5a454ff ("net: ethernet: mtk-star-emac: new driver")
> > Signed-off-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>  
> 
> I'm unsure wether this counts as a bugfix, as no bug was
> seen, and there are quite a few divers that already ignore the return
> from napi_complete_done().
> 
> I don't think the patch is wrong, but maybe it should be sent to
> net-next :/

Agreed, probably the only case where it would matter would be busy
polling. But it's trivial and looks correct, so probably not worth 
the respin