This commit improves the accuracy of the interaction between CPU hotplug operations and RCU's expedited grace periods by using RCU's online-CPU state to determine when failed IPIs should be retried.
Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree_exp.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index 3bc4b3dda801..24343eb87b58 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -385,17 +385,16 @@ retry_ipi: mask_ofl_ipi &= ~mask; continue; } - /* Failed, raced with offline. */ + /* Failed, raced with CPU hotplug operation. */ raw_spin_lock_irqsave_rcu_node(rnp, flags); - if (cpu_online(cpu) && + if ((rnp->qsmaskinitnext & mask) && (rnp->expmask & mask)) { + /* Online, so delay for a bit and try again. */ raw_spin_unlock_irqrestore_rcu_node(rnp, flags); schedule_timeout_uninterruptible(1); - if (cpu_online(cpu) && - (rnp->expmask & mask)) - goto retry_ipi; - raw_spin_lock_irqsave_rcu_node(rnp, flags); + goto retry_ipi; } + /* CPU really is offline, so we can ignore it. */ if (!(rnp->expmask & mask)) mask_ofl_ipi &= ~mask; raw_spin_unlock_irqrestore_rcu_node(rnp, flags); -- 2.5.2
