Commit 047a66d4 authored by David Gibson's avatar David Gibson Committed by Linus Torvalds
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[PATCH] ibmveth: Fix index increment calculation 



The recent commit 751ae21c 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: default avatarDavid Gibson <dwg@au1.ibm.com>
Acked-by: default avatarSantiago 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: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d42552c3

drivers/net/ibmveth.c

+6 −4
Original line number Diff line number Diff line
@@ -212,8 +212,8 @@ static void ibmveth_replenish_buffer_pool(struct ibmveth_adapter *adapter, struc 
			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_pool(struct ibmveth_adapter *adapter, u64 
			 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();

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