linux-kernel - [PATCH v2] mvneta: fix "napi poll" infinite loop

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Message-Id: <20240911112846.285033-1-webmaster@jbsky.fr>
Date: Wed, 11 Sep 2024 13:28:46 +0200
From: Julien Blais <webmaster@...ky.fr>
To: thomas.petazzoni@...tlin.com,
	davem@...emloft.net,
	kuba@...nel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Julien Blais <webmaster@...ky.fr>
Subject: [PATCH v2] mvneta: fix "napi poll" infinite loop

In percpu mode, when there's a network load, one of the cpus can be
solicited without having anything to process.
If 0 is returned to napi poll, napi will ignore the next requests,
causing an infinite loop with ISR handling.

Without this change, patches hang around fixing the queue at 0 and
the interrupt remains stuck on the 1st CPU.
The percpu conf is useless in this case, so we might as well remove it.

Signed-off-by: Julien Blais <webmaster@...ky.fr>
---
 drivers/net/ethernet/marvell/mvneta.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 3f124268b..b6e89b888 100644
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -3186,7 +3186,10 @@ static int mvneta_poll(struct napi_struct *napi, int budget)
 
 	if (rx_done < budget) {
 		cause_rx_tx = 0;
-		napi_complete_done(napi, rx_done);
+		if (rx_done)
+			napi_complete_done(napi, rx_done);
+		else
+			napi_complete(napi);
 
 		if (pp->neta_armada3700) {
 			unsigned long flags;
-- 
2.39.2



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