net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc

stable inclusion
from stable-v6.6.2
commit f9eb4baabdc882b44f2229272516bd8a7f892db2
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8IW7G

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f9eb4baabdc882b44f2229272516bd8a7f892db2



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[ Upstream commit c5bf605ba4f9d6fbbb120595ab95002f4716edcb ]

This patch re-fix the issues mentioned by commit 22a825c5
("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()").

Blocking sending message do solve the issues though, but it also
prevents the peer to receive the final message. Besides, in logic,
whether the sndbuf_desc is NULL or not have no impact on the processing
of cdc message sending.

Hence that, this patch allows the cdc message sending but to check the
sndbuf_desc with care in smc_cdc_tx_handler().

Fixes: 22a825c5 ("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>