[RFT] mv643xxx_eth_start_xmit oops
From: Stephen Hemminger <hidden>
Date: 2006-11-10 19:55:23
Also in:
lkml
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
On Fri, 10 Nov 2006 12:17:45 -0700 Erik Andersen [off-list ref] wrote:
I have a Pegasos2 powerpc system acting as my home server. With 2.6.16.x it was 100% stable and I had months of uptime, rebooting only to periodically apply security updates to the kernel. With 2.6.17 and 2.6.18, after an uptime of no more than 2 days, and usually much less, I get a kernel panic, with nothing in the log. I finally caught it in the act, and took a picture. http://codepoet.org/oops.jpg A quick transcription of the Oops in the screenshot follows: --------------------------------------------
The code int mv643xx_eth_start_xmit is not safe on SMP it was checking for space outside of lock. Does the following (untested) fix it? 0. Fix race where space check is outside of lock. 1. Eliminate bogus BUG_ON()'s 2. Use proper transmit routine return values 3. Cleanup potential kernel log overrun if hit with unaligned frags 4. Compare with actual space needed rather than worst case 5. Use correct return code for case of linearize() failure. --- drivers/net/mv643xx_eth.c | 30 ++++++++++++++---------------- 1 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 9997081..4052bfe 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c@@ -1191,25 +1191,23 @@ static int mv643xx_eth_start_xmit(struct struct net_device_stats *stats = &mp->stats; unsigned long flags; - BUG_ON(netif_queue_stopped(dev)); - BUG_ON(skb == NULL); - - if (mp->tx_ring_size - mp->tx_desc_count < MAX_DESCS_PER_SKB) { - printk(KERN_ERR "%s: transmit with queue full\n", dev->name); - netif_stop_queue(dev); - return 1; - } - - if (has_tiny_unaligned_frags(skb)) { - if (__skb_linearize(skb)) { - stats->tx_dropped++; + if (has_tiny_unaligned_frags(skb) && __skb_linearize(skb)) { + stats->tx_dropped++; + if (net_ratelimit()) printk(KERN_DEBUG "%s: failed to linearize tiny " - "unaligned fragment\n", dev->name); - return 1; - } + "unaligned fragment\n", dev->name); + return NETDEV_TX_OK; } spin_lock_irqsave(&mp->lock, flags); + if (mp->tx_ring_size - mp->tx_desc_count < skb_shinfo(skb)->nr_frags + 1) { + if (!netif_queue_stopped(dev)) { + printk(KERN_ERR "%s: transmit with queue full\n", dev->name); + netif_stop_queue(dev); + } + spin_unlock_irqrestore(&mp->lock, flags); + return NETDEV_TX_BUSY;; + } eth_tx_submit_descs_for_skb(mp, skb); stats->tx_bytes = skb->len;
@@ -1221,7 +1219,7 @@ static int mv643xx_eth_start_xmit(struct spin_unlock_irqrestore(&mp->lock, flags); - return 0; /* success */ + return NETDEV_TX_OK; } /*
--
1.4.1
--
Stephen Hemminger <shemminger@osdl.org>