Some drivers (ab)use the ethtool_ops::get_regs operation to expose
only a hardware revision ID. Commit
a77f5db361 ('ethtool: Allocate register
dump buffer with vmalloc()') had the side-effect of breaking these, as
vmalloc() returns a null pointer for size=0 whereas kmalloc() did not.
For backward-compatibility, allow zero-length dumps again.
Reported-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Cc: stable@kernel.org [2.6.37+]
Signed-off-by: David S. Miller <davem@davemloft.net>
67ae7cf1ee