nfp: fix infinite loop on umapping cleanup

[ Upstream commit eac2c68d663effb077210218788952b5a0c1f60e ]

The while loop that performs the dma page unmapping never decrements
index counter f and hence loops forever. Fix this with a pre-decrement
on f.

Detected by CoverityScan, CID#1357309 ("Infinite loop")

Fixes: 4c3523623dc0 ("net: add driver for Netronome NFP4000/NFP6000 NIC VFs")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
index aee3fd2..4ca82bd 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_net_common.c
@@ -871,8 +871,7 @@ static int nfp_net_tx(struct sk_buff *skb, struct net_device *netdev)
        return NETDEV_TX_OK;
 
 err_unmap:
-       --f;
-       while (f >= 0) {
+       while (--f >= 0) {
                frag = &skb_shinfo(skb)->frags[f];
                dma_unmap_page(&nn->pdev->dev,
                               tx_ring->txbufs[wr_idx].dma_addr,