The rest of the driver assumes at least one free descriptor in the tx ring.
Therefore, since an skb with max frags takes up (MAX_SKB_FRAGS + 1)
descriptors, tx_pending must be > (MAX_SKB_FRAGS + 1).
Signed-off-by: Benjamin Poirier <bpoir...@suse.de>
---
Currently, it is possible to set tx_pending = MAX_SKB_FRAGS + 1. This leads to
a netdev watchdog tx timeout. Depending on whether the previous patches in
this series are applied or not, the timeout happens as soon as tx_pending is
updated or after an skb with max frags is submitted for transmission.
I reproduced this bug using the same approach explained in patch 1.
The bug reproduces with tx_pending = 18
---
drivers/net/ethernet/broadcom/tg3.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/broadcom/tg3.c
b/drivers/net/ethernet/broadcom/tg3.c
index 7022f6d..27e2701 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -12328,7 +12328,7 @@ static int tg3_set_ringparam(struct net_device *dev,
struct ethtool_ringparam *e
if ((ering->rx_pending > tp->rx_std_ring_mask) ||
(ering->rx_jumbo_pending > tp->rx_jmb_ring_mask) ||
(ering->tx_pending > TG3_TX_RING_SIZE - 1) ||
- (ering->tx_pending <= MAX_SKB_FRAGS))
+ (ering->tx_pending <= MAX_SKB_FRAGS + 1))
return -EINVAL;
if (netif_running(dev)) {
--
1.8.4.5
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