rcu: Allow calls to rcu_exit_user_irq from nesting irqs
rcu_exit_user_irq() which exits RCU idle mode after the current
irq returns has been designed to be called from non nesting irqs
only.
However the IPI that restarts the tick and exits RCU user-idle mode
in nohz cpusets can happen anytime. For example it can be a nesting
irq by interrupting a softirq. In this case the stack of RCU API
calls becomes:
==> IRQ
rcu_irq_enter()
....
do_softirq {
===== > IRQ (restart tick IPI)
rcu_irq_enter()
rcu_exit_user_irq()
rcu_irq_exit()
<=====
}
rcu_irq_exit();
Hence we need to make rcu_exit_user_irq() callable from any nesting
level of interrupt.
v2: rcu_user_enter_irq() is only called from non nesting irqs though so
the change doesn't need to be propagated to it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
1 file changed
