diff options
| -rw-r--r-- | kernel/rcupdate.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index f45b91723dc6..48d3bce465b8 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -257,15 +257,23 @@ static void rcu_start_batch(struct rcu_ctrlblk *rcp, struct rcu_state *rsp, if (rcp->next_pending && rcp->completed == rcp->cur) { - /* Can't change, since spin lock held. */ - cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask); - rcp->next_pending = 0; - /* next_pending == 0 must be visible in __rcu_process_callbacks() - * before it can see new value of cur. + /* + * next_pending == 0 must be visible in + * __rcu_process_callbacks() before it can see new value of cur. */ smp_wmb(); rcp->cur++; + + /* + * Accessing nohz_cpu_mask before incrementing rcp->cur needs a + * Barrier Otherwise it can cause tickless idle CPUs to be + * included in rsp->cpumask, which will extend graceperiods + * unnecessarily. + */ + smp_mb(); + cpus_andnot(rsp->cpumask, cpu_online_map, nohz_cpu_mask); + } } |