netdev - [PATCH net 1/3] tsnep: Fix NAPI scheduling

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Message-Id: <20230915210126.74997-2-gerhard@engleder-embedded.com>
Date: Fri, 15 Sep 2023 23:01:24 +0200
From: Gerhard Engleder <gerhard@...leder-embedded.com>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	kuba@...nel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	Gerhard Engleder <gerhard@...leder-embedded.com>
Subject: [PATCH net 1/3] tsnep: Fix NAPI scheduling

According to the NAPI documentation networking/napi.rst, drivers which
have to mask interrupts explicitly should use the napi_schedule_prep()
and __napi_schedule() calls.

No problem seen so far with current implementation. Nevertheless, let's
align the implementation with documentation.

Signed-off-by: Gerhard Engleder <gerhard@...leder-embedded.com>
---
 drivers/net/ethernet/engleder/tsnep_main.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/engleder/tsnep_main.c b/drivers/net/ethernet/engleder/tsnep_main.c
index f61bd89734c5..0cdf0de555ed 100644
--- a/drivers/net/ethernet/engleder/tsnep_main.c
+++ b/drivers/net/ethernet/engleder/tsnep_main.c
@@ -87,8 +87,11 @@ static irqreturn_t tsnep_irq(int irq, void *arg)
 
 	/* handle TX/RX queue 0 interrupt */
 	if ((active & adapter->queue[0].irq_mask) != 0) {
-		tsnep_disable_irq(adapter, adapter->queue[0].irq_mask);
-		napi_schedule(&adapter->queue[0].napi);
+		if (napi_schedule_prep(&adapter->queue[0].napi)) {
+			tsnep_disable_irq(adapter, adapter->queue[0].irq_mask);
+			/* schedule after masking to avoid races */
+			__napi_schedule(&adapter->queue[0].napi);
+		}
 	}
 
 	return IRQ_HANDLED;
@@ -99,8 +102,11 @@ static irqreturn_t tsnep_irq_txrx(int irq, void *arg)
 	struct tsnep_queue *queue = arg;
 
 	/* handle TX/RX queue interrupt */
-	tsnep_disable_irq(queue->adapter, queue->irq_mask);
-	napi_schedule(&queue->napi);
+	if (napi_schedule_prep(&queue->napi)) {
+		tsnep_disable_irq(queue->adapter, queue->irq_mask);
+		/* schedule after masking to avoid races */
+		__napi_schedule(&queue->napi);
+	}
 
 	return IRQ_HANDLED;
 }
-- 
2.30.2