From ebe5236d06abcdb1beb93ffbab73557d5b496824 Mon Sep 17 00:00:00 2001 From: Jeroen De Wachter Date: Mon, 12 Dec 2016 14:29:08 +0100 Subject: [PATCH] encx24j600: bugfix - always move ERXTAIL to next packet in encx24j600_rx_packets Before, encx24j600_rx_packets did not update encx24j600_priv's next_packet member when an error occurred during packet handling (either because the packet's RSV header indicates an error or because the encx24j600_receive_packet method can't allocate an sk_buff). If the next_packet member is not updated, the ERXTAIL register will be set to the same value it had before, which means the bad packet remains in the component's memory and its RSV header will be read again when a new packet arrives. If the RSV header indicates a bad packet or if sk_buff allocation continues to fail, new packets will be stored in the component's memory until that memory is full, after which packets will be dropped. The SETPKTDEC command is always executed though, so the encx24j600 hardware has an incorrect count of the packets in its memory. To prevent this, the next_packet member should always be updated, allowing the packet to be skipped (either because it's bad, as indicated in its RSV header, or because allocating an sk_buff failed). In the allocation failure case, this does mean dropping a valid packet, but dropping the oldest packet to keep as much memory as possible available for new packets seems preferable to keeping old (but valid) packets around while dropping new ones. Signed-off-by: Jeroen De Wachter Signed-off-by: David S. Miller --- drivers/net/ethernet/microchip/encx24j600.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/microchip/encx24j600.c b/drivers/net/ethernet/microchip/encx24j600.c index b14f0305aa31..5251aa3cf4d7 100644 --- a/drivers/net/ethernet/microchip/encx24j600.c +++ b/drivers/net/ethernet/microchip/encx24j600.c @@ -346,7 +346,6 @@ static int encx24j600_receive_packet(struct encx24j600_priv *priv, /* Maintain stats */ dev->stats.rx_packets++; dev->stats.rx_bytes += rsv->len; - priv->next_packet = rsv->next_packet; netif_rx(skb); @@ -383,6 +382,8 @@ static void encx24j600_rx_packets(struct encx24j600_priv *priv, u8 packet_count) encx24j600_receive_packet(priv, &rsv); } + priv->next_packet = rsv.next_packet; + newrxtail = priv->next_packet - 2; if (newrxtail == ENC_RX_BUF_START) newrxtail = SRAM_SIZE - 2; -- 2.20.1