[PATCH v2 0/7] Cleanup task_struct::state

[Peter Zijlstra]

Hi!

The task_struct::state variable is a bit odd in a number of ways:

 - it's declared 'volatile' (against current practises);
 - it's 'unsigned long' which is a weird size;
 - it's type is inconsistent when used for function arguments.

These patches clean that up by making it consistently 'unsigned int', and
replace (almost) all accesses with READ_ONCE()/WRITE_ONCE(). In order to not
miss any, the variable is renamed, ensuring a missed conversion results in a
compile error.

The first few patches fix a number of pre-existing errors and introduce a few
helpers to make the final conversion less painful.

This series applies on top of tip/master, and has been having the all-clear
from the robots for the past week.

Since v1:
 - fixed a whole bunch of compile fail on !x86
 - collected tags
 - (slightly) smaller Cc list


The plan is to stick them in tip/sched/core early next week, I'm hoping this
won't cause too much pain for sfr.