From: Martin Habets <habetsm.xilinx@gmail.com>
Date: Mon, 4 Apr 2022 11:48:51 +0100
Subject: sfc: Do not free an empty page_ring
Patch-mainline: v5.18-rc2
Git-commit: 458f5d92df4807e2a7c803ed928369129996bf96
References: git-fixes
When the page_ring is not used page_ptr_mask is 0.
Do not dereference page_ring[0] in this case.
Fixes: 2768935a4660 ("sfc: reuse pages to avoid DMA mapping/unmapping costs")
Reported-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/ethernet/sfc/rx_common.c | 3 +++
1 file changed, 3 insertions(+)
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -166,6 +166,9 @@ static void efx_fini_rx_recycle_ring(str
struct efx_nic *efx = rx_queue->efx;
int i;
+ if (unlikely(!rx_queue->page_ring))
+ return;
+
/* Unmap and release the pages in the recycle ring. Remove the ring. */
for (i = 0; i <= rx_queue->page_ptr_mask; i++) {
struct page *page = rx_queue->page_ring[i];