[PATCH 5.10 225/294] net: ravb: Always process TX descriptor ring

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

5.10-stable review patch.  If anyone has any objections, please let me know.

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

From: Paul Barker <paul.barker.ct@xxxxxxxxxxxxxx>

[ Upstream commit 596a4254915f94c927217fe09c33a6828f33fb25 ]

The TX queue should be serviced each time the poll function is called,
even if the full RX work budget has been consumed. This prevents
starvation of the TX queue when RX bandwidth usage is high.

Fixes: c156633f1353 ("Renesas Ethernet AVB driver proper")
Signed-off-by: Paul Barker <paul.barker.ct@xxxxxxxxxxxxxx>
Reviewed-by: Sergey Shtylyov <s.shtylyov@xxxxxx>
Link: https://lore.kernel.org/r/20240402145305.82148-1-paul.barker.ct@xxxxxxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/net/ethernet/renesas/ravb_main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 8a4dff0566f7d..b08478aabc6e6 100644
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -911,12 +911,12 @@ static int ravb_poll(struct napi_struct *napi, int budget)
 	int q = napi - priv->napi;
 	int mask = BIT(q);
 	int quota = budget;
+	bool unmask;
 
 	/* Processing RX Descriptor Ring */
 	/* Clear RX interrupt */
 	ravb_write(ndev, ~(mask | RIS0_RESERVED), RIS0);
-	if (ravb_rx(ndev, &quota, q))
-		goto out;
+	unmask = !ravb_rx(ndev, &quota, q);
 
 	/* Processing RX Descriptor Ring */
 	spin_lock_irqsave(&priv->lock, flags);
@@ -926,6 +926,9 @@ static int ravb_poll(struct napi_struct *napi, int budget)
 	netif_wake_subqueue(ndev, q);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
+	if (!unmask)
+		goto out;
+
 	napi_complete(napi);
 
 	/* Re-enable RX/TX interrupts */
-- 
2.43.0