net: axienet: Fix TX ring slot available check

stable inclusion
from stable-v5.10.94
commit 6301f3566aef4e8e8ad6019e43ddb95ad6f65fc6
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6301f3566aef4e8e8ad6019e43ddb95ad6f65fc6



--------------------------------

commit 996defd7 upstream.

The check for whether a TX ring slot was available was incorrect,
since a slot which had been loaded with transmit data but the device had
not started transmitting would be treated as available, potentially
causing non-transmitted slots to be overwritten. The control field in
the descriptor should be checked, rather than the status field (which may
only be updated when the device completes the entry).

Fixes: 8a3b7a25 ("drivers/net/ethernet/xilinx: added Xilinx AXI Ethernet driver")
Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>