From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Joe Damato <joe@dama.to>,
	Linus Walleij <linusw@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 0867/1250] net: ethernet: cortina: Fix budget accounting
Date: Thu, 17 Sep 2026 16:11:02 +0100
Message-ID: <20260917151615.474150625@linuxfoundation.org>
In-Reply-To: <20260917151551.901433442@linuxfoundation.org>
References: <20260917151551.901433442@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linusw@kernel.org>

[ Upstream commit a0de06d0da78a3db53de65dfd7452cc6d111f703 ]

The gmac_rx() function returns the remaining NAPI budget, but its
caller treats the return value as the number of packets received. An
idle poll therefore reports a full budget and remains scheduled.

Return the number of received packets instead. Preserve the existing
free queue refill accounting by adding that count directly; continuing
to subtract it from the budget would invert the refill behavior.

Fixes: 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Link: https://lore.kernel.org/r/20260509-gemini-ethernet-fixes-v1-4-6c5d20ddc35b@kernel.org
Link: https://lore.kernel.org/r/20260512131456.189452-1-pabeni@redhat.com
Assisted-by: LLM
Reviewed-by: Joe Damato <joe@dama.to>
Signed-off-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260903-gemini-ethernet-fixes-v2-1-2bbbd598ca6e@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/cortina/gemini.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/cortina/gemini.c b/drivers/net/ethernet/cortina/gemini.c
index 40bec34f06a7b..aee5cdbf62afb 100644
--- a/drivers/net/ethernet/cortina/gemini.c
+++ b/drivers/net/ethernet/cortina/gemini.c
@@ -1451,6 +1451,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
 	unsigned int frame_len, frag_len;
 	struct gmac_rxdesc *rx = NULL;
 	struct gmac_queue_page *gpage;
+	unsigned int received = 0;
 	union gmac_rxdesc_0 word0;
 	union gmac_rxdesc_1 word1;
 	union gmac_rxdesc_3 word3;
@@ -1546,7 +1547,8 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
 			napi_gro_frags(&port->napi);
 			skb = NULL;
 			frag_nr = 0;
-			--budget;
+			budget--;
+			received++;
 		}
 		continue;
 
@@ -1566,7 +1568,7 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
 	port->rx_skb = skb;
 	port->rx_frag_nr = frag_nr;
 	writew(r, ptr_reg);
-	return budget;
+	return received;
 }
 
 static int gmac_napi_poll(struct napi_struct *napi, int budget)
@@ -1587,7 +1589,7 @@ static int gmac_napi_poll(struct napi_struct *napi, int budget)
 		++port->rx_napi_exits;
 	}
 
-	port->freeq_refill += (budget - received);
+	port->freeq_refill += received;
 	if (port->freeq_refill > freeq_threshold) {
 		port->freeq_refill -= freeq_threshold;
 		geth_fill_freeq(geth, true);
-- 
2.53.0