rcu: Make expedited GPs handle CPU 0 being offline
Currently, the parallelized initialization of expedited grace periods uses
the workqueue associated with each rcu_node structure's ->grplo field.
This works fine unless that CPU is offline. This commit therefore
uses the CPU corresponding to the lowest-numbered online CPU, or just
reports the quiescent states if there are no online CPUs on this rcu_node
structure.
Note that this patch uses cpu_is_offline() instead of the usual
approach of checking bits in the rcu_node structure's ->qsmaskinitnext
field. This is safe because preemption is disabled across both the
cpu_is_offline() check and the call to queue_work_on().
Not-Yet-Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
[ paulmck: Disable preemption to close offline race window. ]
Not-Yet-Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
1 file changed
