[PATCH net v6 2/4] tg3: Fix tx_pending check for MAX_SKB_FRAGS

Benjamin Poirier
2014-09-05T01:31:31Z

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 <bpoirier@suse.de>

---

Changes v1->v2
Moved ahead in the series from 3/3 to 2/3, no functionnal change

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 81b3a57..c5061c3 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -12331,7 +12331,7 @@ 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) ||
(tg3_flag(tp, TSO_BUG) &&
(ering->tx_pending <= (MAX_SKB_FRAGS * 3))))
return -EINVAL;
--
1.8.4.5