[PATCH 5.16 178/285] sfc: Do not free an empty page_ring

Greg Kroah-Hartman
2022-04-12T08:28:50Z

From: Martin Habets <habetsm.xilinx@gmail.com>

[ Upstream commit 458f5d92df4807e2a7c803ed928369129996bf96 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/sfc/rx_common.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/sfc/rx_common.c b/drivers/net/ethernet/sfc/rx_common.c
index 633ca77a26fd..b925de9b4302 100644
--- 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(struct efx_rx_queue *rx_queue)
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];
--
2.35.1