From: Santiago Leon <[EMAIL PROTECTED]>
This patch fixes a nasty bug that has been sitting there since the very first
versions of the driver, but is generating a panic because we changed the number
of 2K buffers for 2.6.16.
The consumer_index and producer_index are u32's that get incremented on every
buffer emptied and replenished respectively. We use the
{producer,consumer}_index mod'ed with the size of the pool to pick out an entry
in the free_map. The problem happens when the u32 rolls over and the number of
the buffers in the pool is not a perfect divisor of 2^32. i.e. if the number
of 2K buffers is 0x300, before the consumer_index rolls over, our index to the
free map = 0xffffffff mod 0x300 = 0xff. The next time a buffer is emptied, we
want the index to the free map to be 0x100, but 0x0 mod 0x300 is 0x0.
This patch assigns the mod'ed result back to the consumer and producer indexes
so that they never roll over. The second chunk of the patch covers the
unlikely case where the consumer_index has just been reset to 0x0 and the
hypervisor is not able to accept that buffer.
Signed-off-by: Santiago Leon <[EMAIL PROTECTED]>
---
drivers/net/ibmveth.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -213,6 +213,7 @@ static void ibmveth_replenish_buffer_poo
}
free_index = pool->consumer_index++ % pool->size;
+ pool->consumer_index = free_index;
index = pool->free_map[free_index];
ibmveth_assert(index != IBM_VETH_INVALID_MAP);
@@ -238,7 +239,10 @@ static void ibmveth_replenish_buffer_poo
if(lpar_rc != H_SUCCESS) {
pool->free_map[free_index] = index;
pool->skbuff[index] = NULL;
- pool->consumer_index--;
+ if (pool->consumer_index == 0)
+ pool->consumer_index = pool->size - 1;
+ else
+ pool->consumer_index--;
dma_unmap_single(&adapter->vdev->dev,
pool->dma_addr[index], pool->buff_size,
DMA_FROM_DEVICE);
@@ -326,6 +330,7 @@ static void ibmveth_remove_buffer_from_p
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;
adapter->rx_buff_pool[pool].free_map[free_index] = index;
mb();
-
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