tree f78a45b8fb6ece2a904cb5733648fc260336e2a6
parent b457a3356a68f242d5ffbd40b6bdeb559d2ae633
author Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1485386929 -0800
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1485446708 -0800

rcu: Make rcu_all_qs() do deferred NOCB wakeups

If a CONFIG_RCU_NOCB_CPUS kernel invokes call_rcu() with interrupts
disabled, wakeups must be deferred in order to avoid self-deadlock in
the cases where the disabled interrupts are due to scheduler locks being
held.  In this case, a flag is set and is checked on entry to extended
quiescent states (usermode, idle), on exit from the RCU_SOFTIRQ handler,
when the CPU in question goes offline, and on a subsequent invocation
of call_rcu().  However, a given CPU could avoid all of those states
for a considerable length of time.

This commit therefore allows an invocation of rcu_all_qs() to do the
wakeup.  It also makes the wakeup function clear the deferred-wakeup flag.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>