The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 1d5a474240407c38ca8c7484a656ee39f585399c Mon Sep 17 00:00:00 2001 From: Martin Habets habetsm.xilinx@gmail.com Date: Sun, 2 Jan 2022 08:41:22 +0000 Subject: [PATCH] sfc: The RX page_ring is optional

The RX page_ring is an optional feature that improves performance. When allocation fails the driver can still function, but possibly with a lower bandwidth. Guard against dereferencing a NULL page_ring.

Fixes: 2768935a4660 ("sfc: reuse pages to avoid DMA mapping/unmapping costs") Signed-off-by: Martin Habets habetsm.xilinx@gmail.com Reported-by: Jiasheng Jiang jiasheng@iscas.ac.cn Link: https://lore.kernel.org/r/164111288276.5798.10330502993729113868.stgit@palan... Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/drivers/net/ethernet/sfc/falcon/rx.c b/drivers/net/ethernet/sfc/falcon/rx.c index 11a6aee852e9..0c6cc2191369 100644 --- a/drivers/net/ethernet/sfc/falcon/rx.c +++ b/drivers/net/ethernet/sfc/falcon/rx.c @@ -110,6 +110,8 @@ static struct page *ef4_reuse_page(struct ef4_rx_queue *rx_queue) struct ef4_rx_page_state *state; unsigned index;

+ if (unlikely(!rx_queue->page_ring)) + return NULL; index = rx_queue->page_remove & rx_queue->page_ptr_mask; page = rx_queue->page_ring[index]; if (page == NULL) @@ -293,6 +295,9 @@ static void ef4_recycle_rx_pages(struct ef4_channel *channel, { struct ef4_rx_queue *rx_queue = ef4_channel_get_rx_queue(channel);

+ if (unlikely(!rx_queue->page_ring)) + return; + do { ef4_recycle_rx_page(channel, rx_buf); rx_buf = ef4_rx_buf_next(rx_queue, rx_buf); diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c index 0983abc0cc5f..633ca77a26fd 100644 --- a/drivers/net/ethernet/sfc/rx_common.c +++ b/drivers/net/ethernet/sfc/rx_common.c @@ -45,6 +45,8 @@ static struct page *efx_reuse_page(struct efx_rx_queue *rx_queue) unsigned int index; struct page *page;

+ if (unlikely(!rx_queue->page_ring)) + return NULL; index = rx_queue->page_remove & rx_queue->page_ptr_mask; page = rx_queue->page_ring[index]; if (page == NULL) @@ -114,6 +116,9 @@ void efx_recycle_rx_pages(struct efx_channel *channel, { struct efx_rx_queue *rx_queue = efx_channel_get_rx_queue(channel);

+ if (unlikely(!rx_queue->page_ring)) + return; + do { efx_recycle_rx_page(channel, rx_buf); rx_buf = efx_rx_buf_next(rx_queue, rx_buf);