net: hns3: fix the concurrency between functions reading debugfs

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4OSRU


CVE: NA

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

[1298504.847848] Call trace:
[1298504.847859] [<ffff000008089e14>] dump_backtrace+0x0/0x23c
[1298504.847865] [<ffff00000808a074>] show_stack+0x24/0x2c
[1298504.847870] [<ffff0000088568a8>] dump_stack+0x84/0xa8
[1298504.847878] [<ffff0000082122fc>] bad_page+0xec/0x14c
[1298504.847883] [<ffff000008219384>] free_pages_check_bad+0x90/0x9c
[1298504.847888] [<ffff00000821307c>] __free_pages_ok+0x2b8/0x2ec
[1298504.847894] [<ffff0000082153ec>] __free_pages+0x44/0x64
[1298504.847900] [<ffff000008288788>] kfree+0x198/0x1a0
[1298504.847905] [<ffff00000823432c>] kvfree+0x3c/0x58
[1298504.847937] [<ffff0000014fabf4>] hns3_dbg_read+0xf4/0x278 [hns3]
[1298504.847944] [<ffff000008359550>] full_proxy_read+0x60/0x90
[1298504.847949] [<ffff0000082b22a4>] __vfs_read+0x58/0x178
[1298504.847952] [<ffff0000082b2454>] vfs_read+0x90/0x14c
[1298504.847956] [<ffff0000082b2b70>] SyS_read+0x60/0xc0

When different functions reading the same debugfs node, it will
cause double free problem, because different functions shared
the same node buffer.

This patch make different functions have their own buffer to fix
the problem.

Fixes: 319ba0a4 ("net: hns3: fix race condition in debugfs")
Fixes: c91910ef ("net: hns3: refactor the debugfs process")
Signed-off-by: Yufeng Mo <moyufeng@huawei.com>
Signed-off-by: Yonglong Liu <liuyonglong@huawei.com>
Reviewed-by: Jian Shen <shenjian15@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>