linux/drivers/net/ethernet/mellanox
Ido Schimmel 5091730d77 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: eda6500a98 ("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>
2016-03-07 11:39:15 -05:00
..
mlx4 net/mlx4_core: Allow resetting VF admin mac to zero 2016-03-02 14:42:46 -05:00
mlx5/core net/mlx5e: Provide correct packet/bytes statistics 2016-03-02 14:37:26 -05:00
mlxsw mlxsw: pci: Correctly determine if descriptor queue is full 2016-03-07 11:39:15 -05:00
Kconfig mlxsw: Introduce Mellanox switch driver core 2015-07-30 00:04:59 -07:00
Makefile mlxsw: Introduce Mellanox switch driver core 2015-07-30 00:04:59 -07:00