net: fec: fix improper use of NETDEV_TX_BUSY

stable inclusion
from stable-v5.10.154
commit c85ee1c3cbc6b3e6e0a10918e49c2266b18089eb
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I64YCB

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c85ee1c3cbc6b3e6e0a10918e49c2266b18089eb



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[ Upstream commit 06a4df58 ]

The ndo_start_xmit() method must not free skb when returning
NETDEV_TX_BUSY, since caller is going to requeue freed skb.

Fix it by returning NETDEV_TX_OK in case of dma_map_single() fails.

Fixes: 79f33912 ("net: fec: Add software TSO support")
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Lipeng Sang <sanglipeng1@jd.com>
(cherry picked from commit a989dc3b)