This is a note to let you know that I've just added the patch titled sfc: The RX page_ring is optional 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: sfc-the-rx-page_ring-is-optional.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. >From 1d5a474240407c38ca8c7484a656ee39f585399c Mon Sep 17 00:00:00 2001 From: Martin Habets <habetsm.xilinx@xxxxxxxxx> Date: Sun, 2 Jan 2022 08:41:22 +0000 Subject: sfc: The RX page_ring is optional From: Martin Habets <habetsm.xilinx@xxxxxxxxx> commit 1d5a474240407c38ca8c7484a656ee39f585399c upstream. 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@xxxxxxxxx> Reported-by: Jiasheng Jiang <jiasheng@xxxxxxxxxxx> Link: https://lore.kernel.org/r/164111288276.5798.10330502993729113868.stgit@xxxxxxxxxxxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/net/ethernet/sfc/falcon/rx.c | 5 +++++ drivers/net/ethernet/sfc/rx_common.c | 5 +++++ 2 files changed, 10 insertions(+) --- 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(struc 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 { 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); --- 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(struc 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_cha { 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); Patches currently in stable-queue which might be from habetsm.xilinx@xxxxxxxxx are queue-5.15/sfc-the-rx-page_ring-is-optional.patch