linux-kernel - [PATCH v4 3/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined

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Message-Id: <1397488277-14865-4-git-send-email-imammedo@redhat.com>
Date:	Mon, 14 Apr 2014 17:11:15 +0200
From:	Igor Mammedov <imammedo@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	x86@...nel.org, imammedo@...hat.com, bp@...e.de,
	paul.gortmaker@...driver.com, JBeulich@...e.com, prarit@...hat.com,
	drjones@...hat.com, toshi.kani@...com, riel@...hat.com,
	gong.chen@...ux.intel.com, andi@...stfloor.org, lenb@...nel.org,
	rjw@...ysocki.net, linux-acpi@...r.kernel.org
Subject: [PATCH v4 3/5] acpi_processor: do not mark present at boot but not onlined CPU as onlined

acpi_processor_add() assumes that present at boot CPUs
are always onlined, it is not so if a CPU failed to become
onlined. As result acpi_processor_add() will mark such CPU
device as onlined in sysfs and following attempts to
online/offline it using /sys/device/system/cpu/cpuX/online
attribute will fail.

Do not poke into device internals in acpi_processor_add()
and touch "struct device { .offline }" attribute, since
for CPUs onlined at boot it's set by:
  topology_init() -> arch_register_cpu() -> register_cpu()
before ACPI device tree is parsed, and for hotplugged
CPUs it's set when userspace onlines CPU via sysfs.

Signed-off-by: Igor Mammedov <imammedo@...hat.com>
---
v2:
 - fix regression in v1 leading to NULL pointer dereference
   on CPU unplug, do not remove "pr->dev = dev;"
---
 drivers/acpi/acpi_processor.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index c29c2c3..42d66f8 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -404,7 +404,6 @@ static int acpi_processor_add(struct acpi_device *device,
 		goto err;
 
 	pr->dev = dev;
-	dev->offline = pr->flags.need_hotplug_init;
 
 	/* Trigger the processor driver's .probe() if present. */
 	if (device_attach(dev) >= 0)
-- 
1.7.1

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