linux-kernel - [PATCH 5.8 38/56] net: lantiq: Disable IRQs only if NAPI gets scheduled

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Message-Id: <20200925124733.582195949@linuxfoundation.org>
Date:   Fri, 25 Sep 2020 14:48:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hauke Mehrtens <hauke@...ke-m.de>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.8 38/56] net: lantiq: Disable IRQs only if NAPI gets scheduled

From: Hauke Mehrtens <hauke@...ke-m.de>

[ Upstream commit 9423361da52356cb68642db5b2729b6b85aad330 ]

The napi_schedule() call will only schedule the NAPI if it is not
already running. To make sure that we do not deactivate interrupts
without scheduling NAPI only deactivate the interrupts in case NAPI also
gets scheduled.

Signed-off-by: Hauke Mehrtens <hauke@...ke-m.de>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/lantiq_xrx200.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -345,10 +345,12 @@ static irqreturn_t xrx200_dma_irq(int ir
 {
 	struct xrx200_chan *ch = ptr;
 
-	ltq_dma_disable_irq(&ch->dma);
-	ltq_dma_ack_irq(&ch->dma);
+	if (napi_schedule_prep(&ch->napi)) {
+		__napi_schedule(&ch->napi);
+		ltq_dma_disable_irq(&ch->dma);
+	}
 
-	napi_schedule(&ch->napi);
+	ltq_dma_ack_irq(&ch->dma);
 
 	return IRQ_HANDLED;
 }