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Date: Sun, 12 Dec 2010 23:06:47 +0100
From: Krzysztof Halasa <khc@...waw.pl>
To: David Miller <davem@...emloft.net>
Cc: <netdev@...r.kernel.org>
Subject: [PATCH] WAN: Fix a TX IRQ causing BUG() in PC300 and PCI200SYN drivers.
We must not wake the TX queue without free TX descriptors.
sca_xmit() expects at least one free descriptor and BUGs otherwise.
Problem reported and fix tested by Bernie Innocenti and Ward Vandewege.
Signed-off-by: Krzysztof HaĆasa <khc@...waw.pl>
--- a/drivers/net/wan/hd64572.c
+++ b/drivers/net/wan/hd64572.c
@@ -293,6 +293,7 @@ static inline void sca_tx_done(port_t *port)
struct net_device *dev = port->netdev;
card_t* card = port->card;
u8 stat;
+ unsigned count = 0;
spin_lock(&port->lock);
@@ -316,10 +317,12 @@ static inline void sca_tx_done(port_t *port)
dev->stats.tx_bytes += readw(&desc->len);
}
writeb(0, &desc->stat); /* Free descriptor */
+ count++;
port->txlast = (port->txlast + 1) % card->tx_ring_buffers;
}
- netif_wake_queue(dev);
+ if (count)
+ netif_wake_queue(dev);
spin_unlock(&port->lock);
}
--
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