linux-kernel - [PATCH v3 11/15] driver: xen: Replace cpu_up/down with device

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Message-Id: <20200223192942.18420-12-qais.yousef@arm.com>
Date:   Sun, 23 Feb 2020 19:29:38 +0000
From:   Qais Yousef <qais.yousef@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     "Paul E . McKenney" <paulmck@...nel.org>,
        Qais Yousef <qais.yousef@....com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Subject: [PATCH v3 11/15] driver: xen: 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.

Reviewed-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Qais Yousef <qais.yousef@....com>
CC: Boris Ostrovsky <boris.ostrovsky@...cle.com>
CC: Juergen Gross <jgross@...e.com>
CC: Stefano Stabellini <sstabellini@...nel.org>
CC: xen-devel@...ts.xenproject.org
CC: linux-kernel@...r.kernel.org
---

Juergen, there's a new add_cpu() which you should be CCed on. I wasn't sure if
I could safely convert this to use it since I couldn't find whether the
notifier already hold the lock or not. If you think remove_cpu() is safe, let
me know and I can send an updated patch.

 drivers/xen/cpu_hotplug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c
index f192b6f42da9..ec975decb5de 100644
--- a/drivers/xen/cpu_hotplug.c
+++ b/drivers/xen/cpu_hotplug.c
@@ -94,7 +94,7 @@ static int setup_cpu_watcher(struct notifier_block *notifier,

 	for_each_possible_cpu(cpu) {
 		if (vcpu_online(cpu) == 0) {
-			(void)cpu_down(cpu);
+			device_offline(get_cpu_device(cpu));
 			set_cpu_present(cpu, false);
 		}
 	}
-- 
2.17.1