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authorIdo Schimmel <idosch@mellanox.com>2016-03-07 15:15:30 +0100
committerDavid S. Miller <davem@davemloft.net>2016-03-07 11:39:15 -0500
commit5091730d7795ccb21eb880699b5194730641c70b (patch)
treeb318dc709a1903a7a542496bbba13e42385d84a4 /drivers/net/ethernet
parent912b1c89c5043e163f8cfa568512a131976121b2 (diff)
downloadlinux-5091730d7795ccb21eb880699b5194730641c70b.tar.bz2
mlxsw: pci: Correctly determine if descriptor queue is full
The descriptor queues for sending (SDQs) and receiving (RDQs) packets are managed by two counters - producer and consumer - which are both 16-bit in size. A queue is considered full when the difference between the two equals the queue's maximum number of descriptors. However, if the producer counter overflows, then it's possible for the full queue check to fail, as it doesn't take the overflow into account. In such a case, descriptors already passed to the device - but for which a completion has yet to be posted - will be overwritten, thereby causing undefined behavior. The above can be achieved under heavy load (~30 netperf instances). Fix that by casting the subtraction result to u16, preventing it from being treated as a signed integer. Fixes: eda6500a987a ("mlxsw: Add PCI bus implementation") Signed-off-by: Ido Schimmel <idosch@mellanox.com> Signed-off-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ethernet')
-rw-r--r--drivers/net/ethernet/mellanox/mlxsw/pci.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/net/ethernet/mellanox/mlxsw/pci.c b/drivers/net/ethernet/mellanox/mlxsw/pci.c
index c071077aafbd..7992c553c1f5 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/pci.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/pci.c
@@ -215,7 +215,7 @@ mlxsw_pci_queue_elem_info_producer_get(struct mlxsw_pci_queue *q)
{
int index = q->producer_counter & (q->count - 1);
- if ((q->producer_counter - q->consumer_counter) == q->count)
+ if ((u16) (q->producer_counter - q->consumer_counter) == q->count)
return NULL;
return mlxsw_pci_queue_elem_info_get(q, index);
}