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>
1 file changed
