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

Eric Dumazet
2012-06-11T08:39:22Z

On Mon, 2012-06-11 at 10:25 +0200, Eric Dumazet wrote:
> On Mon, 2012-06-11 at 10:03 +0200, Roland Stigge wrote:
> > 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 <stigge@antcom.de>
> > Tested-by: Alexandre Pereira da Silva <aletes.xgr@gmail.com>
> >
> > ---
> > 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));
}