Re: [PATCH 1/3] net: lpc_eth: Replace WARN() trace with simple pr_warn()

On Mon, 2012-06-11 at 10:25 +0200, Eric Dumazet wrote:

On Mon, 2012-06-11 at 10:03 +0200, Roland Stigge wrote:

quoted

A WARN() trace indicating a "BUG!" was identified as a "normal" case in the
xmit function in case all TX descriptors are occupied already. In this case,
NETDEV_TX_BUSY is returned, nothing buggy at all.

Signed-off-by: Roland Stigge <redacted>
Tested-by: Alexandre Pereira da Silva <redacted>

---
 drivers/net/ethernet/nxp/lpc_eth.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- linux-2.6.orig/drivers/net/ethernet/nxp/lpc_eth.c
+++ linux-2.6/drivers/net/ethernet/nxp/lpc_eth.c

@@ -1114,7 +1114,7 @@ static int lpc_eth_hard_start_xmit(struc
 		   buffers */
 		netif_stop_queue(ndev);
 		spin_unlock_irq(&pldat->lock);
-		WARN(1, "BUG! TX request when no free TX buffers!\n");
+		pr_warn("Note: TX request when no free TX buffers.\n");
 		return NETDEV_TX_BUSY;
 	}
 

Entering this path is a bug, don't hide it...

Please share with us how this bug was identified as a "normal case" ?

There is an skb leak in this driver, maybe it's the real problem.

diff --git a/drivers/net/ethernet/nxp/lpc_eth.c b/drivers/net/ethernet/nxp/lpc_eth.c
index 8d2666f..0d0f4cb 100644
--- a/drivers/net/ethernet/nxp/lpc_eth.c
+++ b/drivers/net/ethernet/nxp/lpc_eth.c

@@ -946,10 +946,8 @@ static void __lpc_handle_xmit(struct net_device *ndev)
 			/* Update stats */
 			ndev->stats.tx_packets++;
 			ndev->stats.tx_bytes += skb->len;
-
-			/* Free buffer */
-			dev_kfree_skb_irq(skb);
 		}
+		dev_kfree_skb_irq(skb);
 
 		txcidx = readl(LPC_ENET_TXCONSUMEINDEX(pldat->net_base));
 	}