> For example, say I am about to muddle with some members of current. If I
> am in init_module() do I need a spinlock (like lock_kernel())? How about
> in a system call that has no chance of sleeping? From within tq_scheduler?
> What about within a kernel thread? Say I do a "struct task_struct *task =
> current" and then only access members through task; do I still need a
> spinlock at all?
'current' is guaranteed to not go away under you. (that is true on both UP
and SMP). There are certain structures within 'current' that have a
spinlock, the signal structures for example. The rule typically is that if
a structure is completely private to 'current' then you need no spinlock.
Shared fields (eg. 'priority' can be set from another process) have either
the lock_kernel() protection (old, not yet SMP-parallelized code), or some
own spinlock/counter like the signal struct. Does this answer your
question?
-- mingo
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