rcu: Handle NOCB callbacks from irq-disabled idle code
authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tue, 12 Aug 2014 18:27:31 +0000 (11:27 -0700)
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tue, 16 Sep 2014 17:08:03 +0000 (10:08 -0700)
commit1772947bd0126661866069157e95197e9c0020e9
treeda761ad8810ea53199d87602d900652d529c8adb
parent39953dfd40077c7480b1d5deb4d617e086b1c865
rcu: Handle NOCB callbacks from irq-disabled idle code

If an RCU callback is queued on a no-CBs CPU from idle code with irqs
disabled, and if that CPU stays idle forever after, the callback will
never be invoked.  This commit therefore adds a check for this situation
in ____call_rcu_nocb(), invoking the RCU core solely for the purpose
of the ensuing return-to-idle transition.  (If the CPU doesn't return
to idle, the next scheduling-clock interrupt will fix things up.)

Reported-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Paul Gortmaker <paul.gortmaker@windriver.com>
kernel/rcu/tree_plugin.h