[PATCH] 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@au1.ibm.com>
Acked-by: Santiago Leon <santil@us.ibm.com>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index 2802db2..44c9f99 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -212,8 +212,8 @@
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 @@
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();