[PATCH net] sfc: Do not free an empty page_ring

[PATCH net] sfc: Do not free an empty page_ring

[Martin Habets]

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>
---
 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 1b22c7be0088..fa8b9aacca11 100644
--- a/drivers/net/ethernet/sfc/rx_common.c
+++ b/drivers/net/ethernet/sfc/rx_common.c
@@ -150,6 +150,9 @@ 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];

Re: [PATCH net] sfc: Do not free an empty page_ring

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Mon, 04 Apr 2022 11:48:51 +0100 you wrote:
> 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>
> 
> [...]

Here is the summary with links:
  - [net] sfc: Do not free an empty page_ring
    https://git.kernel.org/netdev/net/c/458f5d92df48

You are awesome, thank you!
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