Commit e05121ba authored by Paul E. McKenney's avatar Paul E. McKenney

rcu: Remove CPU-hotplug failsafe from force-quiescent-state code path

Now that quiescent states for newly offlined CPUs are reported either
when that CPU goes offline or at the end of grace-period initialization,
the CPU-hotplug failsafe in the force-quiescent-state code path is no
longer needed.

This commit therefore removes this failsafe.
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent 17a8212b
...@@ -391,11 +391,11 @@ TRACE_EVENT(rcu_quiescent_state_report, ...@@ -391,11 +391,11 @@ TRACE_EVENT(rcu_quiescent_state_report,
/* /*
* Tracepoint for quiescent states detected by force_quiescent_state(). * Tracepoint for quiescent states detected by force_quiescent_state().
* These trace events include the type of RCU, the grace-period number that * These trace events include the type of RCU, the grace-period number
* was blocked by the CPU, the CPU itself, and the type of quiescent state, * that was blocked by the CPU, the CPU itself, and the type of quiescent
* which can be "dti" for dyntick-idle mode, "ofl" for CPU offline, "kick" * state, which can be "dti" for dyntick-idle mode, "kick" when kicking
* when kicking a CPU that has been in dyntick-idle mode for too long, or * a CPU that has been in dyntick-idle mode for too long, or "rqc" if the
* "rqc" if the CPU got a quiescent state via its rcu_qs_ctr. * CPU got a quiescent state via its rcu_qs_ctr.
*/ */
TRACE_EVENT(rcu_fqs, TRACE_EVENT(rcu_fqs,
......
...@@ -1188,14 +1188,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) ...@@ -1188,14 +1188,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
smp_store_release(ruqp, true); smp_store_release(ruqp, true);
} }
/* Check for the CPU being offline. */
if (!(rdp->grpmask & rcu_rnp_online_cpus(rnp))) {
trace_rcu_fqs(rdp->rsp->name, rdp->gp_seq, rdp->cpu, TPS("ofl"));
rdp->offline_fqs++;
rcu_gpnum_ovf(rnp, rdp);
return 1;
}
/* /*
* A CPU running for an extended time within the kernel can * A CPU running for an extended time within the kernel can
* delay RCU grace periods. When the CPU is in NO_HZ_FULL mode, * delay RCU grace periods. When the CPU is in NO_HZ_FULL mode,
...@@ -3718,6 +3710,7 @@ void rcu_cpu_starting(unsigned int cpu) ...@@ -3718,6 +3710,7 @@ void rcu_cpu_starting(unsigned int cpu)
nbits = bitmap_weight(&oldmask, BITS_PER_LONG); nbits = bitmap_weight(&oldmask, BITS_PER_LONG);
/* Allow lockless access for expedited grace periods. */ /* Allow lockless access for expedited grace periods. */
smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */ smp_store_release(&rsp->ncpus, rsp->ncpus + nbits); /* ^^^ */
rcu_gpnum_ovf(rnp, rdp); /* Offline-induced counter wrap? */
if (rnp->qsmask & mask) { /* RCU waiting on incoming CPU? */ if (rnp->qsmask & mask) { /* RCU waiting on incoming CPU? */
/* Report QS -after- changing ->qsmaskinitnext! */ /* Report QS -after- changing ->qsmaskinitnext! */
rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags); rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags);
......
...@@ -217,7 +217,6 @@ struct rcu_data { ...@@ -217,7 +217,6 @@ struct rcu_data {
/* 4) reasons this CPU needed to be kicked by force_quiescent_state */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */
unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
unsigned long offline_fqs; /* Kicked due to being offline. */
unsigned long cond_resched_completed; unsigned long cond_resched_completed;
/* Grace period that needs help */ /* Grace period that needs help */
/* from cond_resched(). */ /* from cond_resched(). */
......
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