[PATCH V3 0/1] livepatch: Add "stack_order" sysfs attribute

[Wardenjohn <zhangwarden@gmail.com>]

As previous discussion, maintainers think that patch-level sysfs interface is the
only acceptable way to maintain the information of the order that klp_patch is 
applied to the system.

However, the previous patch introduce klp_ops into klp_func is a optimization 
methods of the patch introducing 'using' feature to klp_func.

But now, we don't support 'using' feature to klp_func and make 'klp_ops' patch
not necessary.

Therefore, this new version is only introduce the sysfs feature of klp_patch 
'stack_order'.

V1 -> V2:
1. According to the suggestion from Petr, to make the meaning more clear, rename
'order' to 'stack_order'.
2. According to the suggestion from Petr and Miroslav, this patch now move the 
calculating process to stack_order_show function. Adding klp_mutex lock protection.

V2 -> V3:
1. Squash 2 patches into 1. Update description of stack_order in ABI Document.
(Suggested by Miroslav)
2. Update subject and commit log. (Suggested by Miroslav)
3. Update code format for some line of the patch. (Suggested by Miroslav)

Regards.
Wardenjohn.