there's a problem in #5's rcu_read_lock():
void
rcu_read_lock(void)
{
preempt_disable();
if (current->rcu_read_lock_nesting++ == 0) {
current->rcu_read_lock_ptr =
&__get_cpu_var(rcu_data).lock;
read_lock(current->rcu_read_lock_ptr);
}
preempt_enable();
}
not only are read_lock()-ed sections preemptible, read_lock() itself may
block, so it cannot be called from within preempt_disable(). How about
something like:
void
rcu_read_lock(void)
{
preempt_disable();
if (current->rcu_read_lock_nesting++ == 0) {
current->rcu_read_lock_ptr =
&__get_cpu_var(rcu_data).lock;
preempt_enable();
read_lock(current->rcu_read_lock_ptr);
} else
preempt_enable();
}
this would still make it 'statistically scalable' - but is it correct?
Ingo
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