This is a note to let you know that I've just added the patch titled net: macb: Increment rx bd head after allocating skb and buffer to the 5.15-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-macb-increment-rx-bd-head-after-allocating-skb-a.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 7ad07ac2150dd471f3d5c388de495a9a7245e004 Author: Harini Katakam <harini.katakam@xxxxxxxxxx> Date: Thu May 12 22:49:00 2022 +0530 net: macb: Increment rx bd head after allocating skb and buffer [ Upstream commit 9500acc631dbb8b73166e25700e656b11f6007b6 ] 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@xxxxxxxxxx> Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx> Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxxxxx> Reviewed-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220512171900.32593-1-harini.katakam@xxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c index 217c1a0f8940..2fd3dd4b8b81 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 */