linux-kernel - [PATCH v2 06/14] powerpc: Replace cpu_up/down with device

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Date:   Mon, 25 Nov 2019 11:27:46 +0000
From:   Qais Yousef <qais.yousef@....com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Qais Yousef <qais.yousef@....com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Enrico Weigelt <info@...ux.net>, Ram Pai <linuxram@...ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Christophe Leroy <christophe.leroy@....fr>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 06/14] powerpc: Replace cpu_up/down with device_online/offline

The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down.

See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.

This also prepares to make cpu_up/down a private interface for anything
but the cpu subsystem.

Acked-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Qais Yousef <qais.yousef@....com>
CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC: Paul Mackerras <paulus@...ba.org>
CC: Michael Ellerman <mpe@...erman.id.au>
CC: Enrico Weigelt <info@...ux.net>
CC: Ram Pai <linuxram@...ibm.com>
CC: Nicholas Piggin <npiggin@...il.com>
CC: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
CC: Christophe Leroy <christophe.leroy@....fr>
CC: Thomas Gleixner <tglx@...utronix.de>
CC: linuxppc-dev@...ts.ozlabs.org
CC: linux-kernel@...r.kernel.org
---
 arch/powerpc/kernel/machine_kexec_64.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 04a7cba58eff..ebf8cc7acc4d 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -208,13 +208,15 @@ static void wake_offline_cpus(void)
 {
 	int cpu = 0;
 
+	lock_device_hotplug();
 	for_each_present_cpu(cpu) {
 		if (!cpu_online(cpu)) {
 			printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
 			       cpu);
-			WARN_ON(cpu_up(cpu));
+			WARN_ON(device_online(get_cpu_device(cpu)));
 		}
 	}
+	unlock_device_hotplug();
 }
 
 static void kexec_prepare_cpus(void)
-- 
2.17.1