linux-kernel - [tip:smp/hotplug] KVM/PPC/Book3S HV: Use cpuhp_setup_state_nocalls

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Date:   Fri, 26 May 2017 01:36:42 -0700
From:   tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     rostedt@...dmis.org, bigeasy@...utronix.de,
        benh@...nel.crashing.org, mingo@...nel.org,
        paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
        tglx@...utronix.de, hpa@...or.com, mpe@...erman.id.au,
        agraf@...e.com, linux-kernel@...r.kernel.org
Subject: [tip:smp/hotplug] KVM/PPC/Book3S HV: Use
 cpuhp_setup_state_nocalls_cpuslocked()

Commit-ID:  419af25fa4d0974fd758a668c08c369c19392a47
Gitweb:     http://git.kernel.org/tip/419af25fa4d0974fd758a668c08c369c19392a47
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Wed, 24 May 2017 10:15:21 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 26 May 2017 10:10:39 +0200

KVM/PPC/Book3S HV: Use cpuhp_setup_state_nocalls_cpuslocked()

kvmppc_alloc_host_rm_ops() holds get_online_cpus() while invoking
cpuhp_setup_state_nocalls().

cpuhp_setup_state_nocalls() invokes get_online_cpus() as well. This is
correct, but prevents the conversion of the hotplug locking to a percpu
rwsem.

Use cpuhp_setup_state_nocalls_cpuslocked() to avoid the nested
call. Convert *_online_cpus() to the new interfaces while at it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Ingo Molnar <mingo@...nel.org>
Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
Cc: kvm@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: kvm-ppc@...r.kernel.org
Cc: Michael Ellerman <mpe@...erman.id.au>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: Alexander Graf <agraf@...e.com>
Link: http://lkml.kernel.org/r/20170524081547.809616236@linutronix.de

---
 arch/powerpc/kvm/book3s_hv.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 42b7a4f..48a6bd1 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3317,7 +3317,7 @@ void kvmppc_alloc_host_rm_ops(void)
 		return;
 	}

-	get_online_cpus();
+	cpus_read_lock();

 	for (cpu = 0; cpu < nr_cpu_ids; cpu += threads_per_core) {
 		if (!cpu_online(cpu))
@@ -3339,17 +3339,17 @@ void kvmppc_alloc_host_rm_ops(void)
 	l_ops = (unsigned long) ops;

 	if (cmpxchg64((unsigned long *)&kvmppc_host_rm_ops_hv, 0, l_ops)) {
-		put_online_cpus();
+		cpus_read_unlock();
 		kfree(ops->rm_core);
 		kfree(ops);
 		return;
 	}

-	cpuhp_setup_state_nocalls(CPUHP_KVM_PPC_BOOK3S_PREPARE,
-				  "ppc/kvm_book3s:prepare",
-				  kvmppc_set_host_core,
-				  kvmppc_clear_host_core);
-	put_online_cpus();
+	cpuhp_setup_state_nocalls_cpuslocked(CPUHP_KVM_PPC_BOOK3S_PREPARE,
+					     "ppc/kvm_book3s:prepare",
+					     kvmppc_set_host_core,
+					     kvmppc_clear_host_core);
+	cpus_read_unlock();
 }

 void kvmppc_free_host_rm_ops(void)