linux-kernel - [PATCH net 2/2] net: lantiq_xrx200: fix return value in ENOMEM case

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Date:   Sun, 17 Jul 2022 21:48:24 +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 2/2] net: lantiq_xrx200: fix return value in ENOMEM case

The xrx200_hw_receive() function can return:
* XRX200_DMA_PACKET_IN_PROGRESS (the next descriptor contains the
further part of the packet),
* XRX200_DMA_PACKET_COMPLETE (a complete packet has been received),
* -ENOMEM (a memory allocation error occurred).

Currently, the third of these cases is incorrectly handled. The NAPI
poll function returns then a negative value (-ENOMEM). Correctly in
such a situation, the driver should try to receive next packet in
the hope that this time the memory allocation for the next descriptor
will succeed.

This patch replaces the XRX200_DMA_PACKET_IN_PROGRESS definition with
-EINPROGRESS to simplify the driver.

Fixes: c3e6b2c35b34 ("net: lantiq_xrx200: add ingress SG DMA support")
Signed-off-by: Aleksander Jan Bajkowski <olek2@...pl>
---
 drivers/net/ethernet/lantiq_xrx200.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/lantiq_xrx200.c b/drivers/net/ethernet/lantiq_xrx200.c
index 6a83a6c19484..2865d07f3fc8 100644
--- a/drivers/net/ethernet/lantiq_xrx200.c
+++ b/drivers/net/ethernet/lantiq_xrx200.c
@@ -27,9 +27,6 @@
 #define XRX200_DMA_TX		1
 #define XRX200_DMA_BURST_LEN	8
 
-#define XRX200_DMA_PACKET_COMPLETE	0
-#define XRX200_DMA_PACKET_IN_PROGRESS	1
-
 /* cpu port mac */
 #define PMAC_RX_IPG		0x0024
 #define PMAC_RX_IPG_MASK	0xf
@@ -272,9 +269,8 @@ static int xrx200_hw_receive(struct xrx200_chan *ch)
 		netif_receive_skb(ch->skb_head);
 		ch->skb_head = NULL;
 		ch->skb_tail = NULL;
-		ret = XRX200_DMA_PACKET_COMPLETE;
 	} else {
-		ret = XRX200_DMA_PACKET_IN_PROGRESS;
+		ret = -EINPROGRESS;
 	}
 
 	return ret;
@@ -292,10 +288,8 @@ static int xrx200_poll_rx(struct napi_struct *napi, int budget)
 
 		if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) == LTQ_DMA_C) {
 			ret = xrx200_hw_receive(ch);
-			if (ret == XRX200_DMA_PACKET_IN_PROGRESS)
+			if (ret)
 				continue;
-			if (ret != XRX200_DMA_PACKET_COMPLETE)
-				return ret;
 			rx++;
 		} else {
 			break;
-- 
2.30.2