linux-kernel - [PATCH net v3 2/3] net: lantiq_xrx200: fix lock under memory pressure

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Message-Id: <20220824215408.4695-3-olek2@wp.pl>
Date:   Wed, 24 Aug 2022 23:54:07 +0200
From:   Aleksander Jan Bajkowski <olek2@...pl>
To:     hauke@...ke-m.de, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, olek2@...pl,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net v3 2/3] net: lantiq_xrx200: fix lock under memory pressure

When the xrx200_hw_receive() function returns -ENOMEM, the NAPI poll
function immediately returns an error.
This is incorrect for two reasons:
* the function terminates without enabling interrupts or scheduling NAPI,
* the error code (-ENOMEM) is returned instead of the number of received
packets.

After the first memory allocation failure occurs, packet reception is
locked due to disabled interrupts from DMA..

Fixes: fe1a56420cf2 ("net: lantiq: Add Lantiq / Intel VRX200 Ethernet driver")
Signed-off-by: Aleksander Jan Bajkowski <olek2@...pl>
---
 drivers/net/ethernet/lantiq_xrx200.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 89314b645c82..25adce7f0c7c 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -294,7 +294,7 @@ static int xrx200_poll_rx(struct napi_struct *napi, int budget)
 			if (ret == XRX200_DMA_PACKET_IN_PROGRESS)
 				continue;
 			if (ret != XRX200_DMA_PACKET_COMPLETE)
-				return ret;
+				break;
 			rx++;
 		} else {
 			break;
-- 
2.30.2