Patch "net: ravb: Always process TX descriptor ring" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: ravb: Always process TX descriptor ring

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-ravb-always-process-tx-descriptor-ring.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4883d63eac0be55a2bb60213d4a44a5a3c31f29c
Author: Paul Barker <paul.barker.ct@xxxxxxxxxxxxxx>
Date:   Tue Apr 2 15:53:04 2024 +0100

    net: ravb: Always process TX descriptor ring
    
    [ 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>

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index 53b9c77c7f6a7..3cc312a526d9b 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 */