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rcu: Exclude RCU-offline CPUs from expedited grace periods 

The expedited RCU grace periods currently rely on a failure indication
from smp_call_function_single() to determine that a given CPU is offline.
This works after a fashion, but is more contorted and less precise than
relying on RCU's internal state.  This commit therefore takes a first
step towards relying on internal state.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney 2016-06-29 17:04:19 -07:00
parent 24a6cff286
commit 98834b8378
1 changed files with 2 additions and 1 deletions
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3
kernel/rcu/tree_exp.h
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@ -359,7 +359,8 @@ static void sync_rcu_exp_select_cpus(struct rcu_state *rsp,
struct rcu_dynticks *rdtp = &per_cpu(rcu_dynticks, cpu);
if (raw_smp_processor_id() == cpu ||
!(atomic_add_return(0, &rdtp->dynticks) & 0x1))
!(atomic_add_return(0, &rdtp->dynticks) & 0x1) ||
!(rnp->qsmaskinitnext & rdp->grpmask))
mask_ofl_test |= rdp->grpmask;
}
mask_ofl_ipi = rnp->expmask & ~mask_ofl_test;