From 7fa326ed38b3c1ef9a8ec06388d8ea56adc61bdb Mon Sep 17 00:00:00 2001
From: Harini Katakam <harini.katakam@xilinx.com>
Date: Thu, 12 May 2022 22:49:00 +0530
Subject: [PATCH 23/34] net: macb: Increment rx bd head after allocating skb
 and buffer
Git-commit: 9500acc631dbb8b73166e25700e656b11f6007b6
Patch-mainline: v5.18
References: git-fixes

In gem_rx_refill rx_prepared_head is incremented at the beginning of
the while loop preparing the skb and data buffers. If the skb or data
buffer allocation fails, this BD will be unusable BDs until the head
loops back to the same BD (and obviously buffer allocation succeeds).
In the unlikely event that there's a string of allocation failures,
there will be an equal number of unusable BDs and an inconsistent RX
BD chain. Hence increment the head at the end of the while loop to be
clean.

Fixes: 4df95131ea80 ("net/macb: change RX path for GEM")
Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220512171900.32593-1-harini.katakam@xilinx.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 61e05c6c4cdd..89c253739822 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1250,7 +1250,6 @@ static void gem_rx_refill(struct macb_queue *queue)
 		/* Make hw descriptor updates visible to CPU */
 		rmb();
 
-		queue->rx_prepared_head++;
 		desc = macb_rx_desc(queue, entry);
 
 		if (!queue->rx_skbuff[entry]) {
@@ -1289,6 +1288,7 @@ static void gem_rx_refill(struct macb_queue *queue)
 			dma_wmb();
 			desc->addr &= ~MACB_BIT(RX_USED);
 		}
+		queue->rx_prepared_head++;
 	}
 
 	/* Make descriptor updates visible to hardware */
-- 
2.16.4