anolis: net/smc: Avoid clcsock access panic

anolis inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I79GVV
CVE: NA

Reference: https://gitee.com/anolis/cloud-kernel/commit/6111a29e707fe83f89eb4dedc22e401b3c544389



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ANBZ: #1742

This patch is a set of the workaround for clcsock access panic.

There are two kinds of invalid access of clcsock.
1) Access smc->clcsock when smc->clcsock is reset to NULL;
2) Access smc->clcsock->sk when sock_release(clcsock);

In upstream implementation, only 1) happens, and it is fixed by
c0bf3d8a ("net/smc: Transitional solution for clcsock race
issue").

In anolis implementation, 1) and 2) are both reproduced. They
are mainly triggered by c5e5a9f9c5d8 ("net/smc: Keep first contact
clcsock"). In anolis smc implementation, The first contact's
clcsock is saved in link struct and may be released during smc
link clear. After that, if smc->clcsock is accessed, a NULL pointer
panic will happen.

This patch provides a workaround for these. To eradicate such
issues, We may need to avoid using first contact's clcsock as
erdma link.

Fixes: c0bf3d8a ("net/smc: Transitional solution for clcsock race issue").
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Acked-by: Tony Lu <tonylu@linux.alibaba.com>
Link: https://gitee.com/anolis/cloud-kernel/pulls/577


Signed-off-by: Gengbiao Shen <shengengbiao@sangfor.com.cn>