netdev - [PATCH net 6/7] iavf: Fix handling of dummy receive descriptors

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Date:   Mon, 11 Jul 2022 16:02:42 -0700
From:   Tony Nguyen <anthony.l.nguyen@...el.com>
To:     davem@...emloft.net, kuba@...nel.org, pabeni@...hat.com,
        edumazet@...gle.com
Cc:     Przemyslaw Patynowski <przemyslawx.patynowski@...el.com>,
        netdev@...r.kernel.org, anthony.l.nguyen@...el.com,
        Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Konrad Jankowski <konrad0.jankowski@...el.com>
Subject: [PATCH net 6/7] iavf: Fix handling of dummy receive descriptors

From: Przemyslaw Patynowski <przemyslawx.patynowski@...el.com>

Fix memory leak caused by not handling dummy receive descriptor properly.
iavf_get_rx_buffer now sets the rx_buffer return value for dummy receive
descriptors. Without this patch, when the hardware writes a dummy
descriptor, iavf would not free the page allocated for the previous receive
buffer. This is an unlikely event but can still happen.

[Jesse: massaged commit message]

Fixes: efa14c398582 ("iavf: allow null RX descriptors")
Signed-off-by: Przemyslaw Patynowski <przemyslawx.patynowski@...el.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@...el.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@...el.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@...el.com>
---
 drivers/net/ethernet/intel/iavf/iavf_txrx.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/iavf/iavf_txrx.c b/drivers/net/ethernet/intel/iavf/iavf_txrx.c
index 7bf8c25dc824..06d18797d25a 100644
--- a/drivers/net/ethernet/intel/iavf/iavf_txrx.c
+++ b/drivers/net/ethernet/intel/iavf/iavf_txrx.c
@@ -1285,11 +1285,10 @@ static struct iavf_rx_buffer *iavf_get_rx_buffer(struct iavf_ring *rx_ring,
 {
 	struct iavf_rx_buffer *rx_buffer;
 
-	if (!size)
-		return NULL;
-
 	rx_buffer = &rx_ring->rx_bi[rx_ring->next_to_clean];
 	prefetchw(rx_buffer->page);
+	if (!size)
+		return rx_buffer;
 
 	/* we are reusing so sync this buffer for CPU use */
 	dma_sync_single_range_for_cpu(rx_ring->dev,
-- 
2.35.1