Patch "net: macb: fix the RX queue reset in macb_rx()" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

net: macb: fix the RX queue reset in macb_rx()

to the 4.8-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:
net-macb-fix-the-rx-queue-reset-in-macb_rx.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Cyrille Pitchen <[email protected]>
Date: Mon, 28 Nov 2016 14:40:55 +0100
Subject: net: macb: fix the RX queue reset in macb_rx()

From: Cyrille Pitchen <[email protected]>

[ Upstream commit a0b44eea372b449ef9744fb1d90491cc063289b8 ]

On macb only (not gem), when a RX queue corruption was detected from macb_rx(), the RX queue was reset: during this process the RX ring buffer descriptor was initialized by macb_init_rx_ring() but we forgot to also set bp->rx_tail to 0.

Indeed, when processing the received frames, bp->rx_tail provides the macb driver with the index in the RX ring buffer of the next buffer to process. So when the whole ring buffer is reset we must also reset bp->rx_tail so the driver is synchronized again with the hardware.

Since macb_init_rx_ring() is called from many locations, currently from macb_rx() and macb_init_rings(), we'd rather add the "bp->rx_tail = 0;" line inside macb_init_rx_ring() than add the very same line after each call of this function.

Without this fix, the rx queue is not reset properly to recover from queue corruption and connection drop may occur.

---
 drivers/net/ethernet/cadence/macb.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

@@ -959,6 +959,7 @@ static inline void macb_init_rx_ring(str
 		addr += bp->rx_buffer_size;
 	}
 	bp->rx_ring[RX_RING_SIZE - 1].addr |= MACB_BIT(RX_WRAP);
+	bp->rx_tail = 0;
 }
 
 static int macb_rx(struct macb *bp, int budget)

@@ -1597,8 +1598,6 @@ static void macb_init_rings(struct macb
 	bp->queues[0].tx_head = 0;
 	bp->queues[0].tx_tail = 0;
 	bp->queues[0].tx_ring[TX_RING_SIZE - 1].ctrl |= MACB_BIT(TX_WRAP);
-
-	bp->rx_tail = 0;
 }
 
 static void macb_reset_hw(struct macb *bp)

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/net-macb-fix-the-rx-queue-reset-in-macb_rx.patch