linux-kernel - [PATCH net v2 2/2] net: ethernet: mtk-star-emac: rearm interrupts in rx

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Message-Id: <20250424-mtk_star_emac-fix-spinlock-recursion-issue-v2-2-f3fde2e529d8@collabora.com>
Date: Thu, 24 Apr 2025 10:38:49 +0200
From: Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
To: Felix Fietkau <nbd@....name>, Sean Wang <sean.wang@...iatek.com>, 
 Lorenzo Bianconi <lorenzo@...nel.org>, Andrew Lunn <andrew+netdev@...n.ch>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Biao Huang <biao.huang@...iatek.com>, 
 Yinghua Pan <ot_yinghua.pan@...iatek.com>, 
 Bartosz Golaszewski <brgl@...ev.pl>
Cc: kernel@...labora.com, netdev@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-mediatek@...ts.infradead.org, 
 Louis-Alexis Eyraud <louisalexis.eyraud@...labora.com>
Subject: [PATCH net v2 2/2] net: ethernet: mtk-star-emac: rearm interrupts
 in rx_poll only when advised

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@...labora.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