From: Paul E. McKenney Date: Thu, 30 Jun 2016 00:04:19 +0000 (-0700) Subject: rcu: Exclude RCU-offline CPUs from expedited grace periods X-Git-Tag: v4.9-rc1~168^2^2^2~1 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=98834b83785e1388fa8672cf4f8de09974d15e86;p=linux.git 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 --- diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index f316683b18f1..3bc4b3dda801 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -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;