Commit-ID: e05121ba5b81e2f85349f038642410578457f6db
Gitweb: https://git.kernel.org/tip/e05121ba5b81e2f85349f038642410578457f6db
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Mon, 7 May 2018 12:07:48 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 12 Jul 2018 15:39:07 -0700
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: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/trace/events/rcu.h | 10 +++++-----
kernel/rcu/tree.c | 9 +--------
kernel/rcu/tree.h | 1 -
3 files changed, 6 insertions(+), 14 deletions(-)
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index 759e7e83733d..a8d07feff6a0 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -391,11 +391,11 @@ TRACE_EVENT(rcu_quiescent_state_report,
/*
* Tracepoint for quiescent states detected by force_quiescent_state().
- * These trace events include the type of RCU, the grace-period number that
- * was blocked by the CPU, the CPU itself, and the type of quiescent state,
- * which can be "dti" for dyntick-idle mode, "ofl" for CPU offline, "kick"
- * when kicking a CPU that has been in dyntick-idle mode for too long, or
- * "rqc" if the CPU got a quiescent state via its rcu_qs_ctr.
+ * These trace events include the type of RCU, the grace-period number
+ * that was blocked by the CPU, the CPU itself, and the type of quiescent
+ * state, which can be "dti" for dyntick-idle mode, "kick" when kicking
+ * a CPU that has been in dyntick-idle mode for too long, or "rqc" if the
+ * CPU got a quiescent state via its rcu_qs_ctr.
*/
TRACE_EVENT(rcu_fqs,
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 770f0df54015..5f1a11f1f7bc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1188,14 +1188,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp)
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
* delay RCU grace periods. When the CPU is in NO_HZ_FULL mode,
@@ -3718,6 +3710,7 @@ void rcu_cpu_starting(unsigned int cpu)
nbits = bitmap_weight(&oldmask, BITS_PER_LONG);
/* Allow lockless access for expedited grace periods. */
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? */
/* Report QS -after- changing ->qsmaskinitnext! */
rcu_report_qs_rnp(mask, rsp, rnp, rnp->gp_seq, flags);
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 6683da6e4ecc..795d469c6f67 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -217,7 +217,6 @@ struct rcu_data {
/* 4) reasons this CPU needed to be kicked by force_quiescent_state */
unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */
- unsigned long offline_fqs; /* Kicked due to being offline. */
unsigned long cond_resched_completed;
/* Grace period that needs help */
/* from cond_resched(). */
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|