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Message-ID: <20061016014334.GA30921@localhost.localdomain>
Date: Mon, 16 Oct 2006 11:43:34 +1000
From: David Gibson <dwg@....ibm.com>
To: Yao Fei Zhu <walkinair@...ibm.com>
Cc: linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org
Subject: Re: Failed to boot kernel 2.6.19-rc2 due to IBM veth problem.
On Mon, Oct 16, 2006 at 12:26:37AM +0800, Yao Fei Zhu wrote:
> Hi, all,
>
> Boot kernel 2.6.19-rc2 on IBM System P5 partitions will fall into xmon.
> Here is the boot log,
This is probably the same bug I recently posted about. The patch
below should fix it.
ibmveth: Fix index increment calculation
The recent commit 751ae21c6cd1493e3d0a4935b08fb298b9d89773 introduced
a bug in the producer/consumer index calculation in the ibmveth driver
- incautious use of the post-increment ++ operator resulted in an
increment being immediately reverted. This patch corrects the logic.
Without this patch, the driver oopses almost immediately after
activation on at least some machines.
Signed-off-by: David Gibson <dwg@....ibm.com>
Index: working-2.6/drivers/net/ibmveth.c
===================================================================
--- working-2.6.orig/drivers/net/ibmveth.c 2006-10-13 14:19:54.000000000 +1000
+++ working-2.6/drivers/net/ibmveth.c 2006-10-13 14:19:59.000000000 +1000
@@ -212,8 +212,8 @@ static void ibmveth_replenish_buffer_poo
break;
}
- free_index = pool->consumer_index++ % pool->size;
- pool->consumer_index = free_index;
+ free_index = pool->consumer_index;
+ pool->consumer_index = (pool->consumer_index + 1) % pool->size;
index = pool->free_map[free_index];
ibmveth_assert(index != IBM_VETH_INVALID_MAP);
@@ -329,8 +329,10 @@ static void ibmveth_remove_buffer_from_p
adapter->rx_buff_pool[pool].buff_size,
DMA_FROM_DEVICE);
- free_index = adapter->rx_buff_pool[pool].producer_index++ % adapter->rx_buff_pool[pool].size;
- adapter->rx_buff_pool[pool].producer_index = free_index;
+ free_index = adapter->rx_buff_pool[pool].producer_index;
+ adapter->rx_buff_pool[pool].producer_index
+ = (adapter->rx_buff_pool[pool].producer_index + 1)
+ % adapter->rx_buff_pool[pool].size;
adapter->rx_buff_pool[pool].free_map[free_index] = index;
mb();
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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