linux-kernel - [PATCH v2 1/2] acpi : cpu hot-remove returns error when cpu

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Date:	Fri, 26 Oct 2012 18:25:42 +0900
From:	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
CC:	<srivatsa.bhat@...ux.vnet.ibm.com>, <toshi.kani@...com>,
	<lenb@...nel.org>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v2 1/2] acpi : cpu hot-remove returns error when cpu_down()
 fails


v1 -> v2
- update Rafael's comment.

>>   static int acpi_processor_handle_eject(struct acpi_processor *pr)
>>   {
>> -    if (cpu_online(pr->id))
>> -        cpu_down(pr->id);
>> +    int ret = 0;
>> +
>> +    if (cpu_online(pr->id)) {
>> +        ret = cpu_down(pr->id);
>
> If you defined ret here ...
>
>> +        if (ret)
>> +            return ret;
>> +    }
>>

>>       arch_unregister_cpu(pr->id);
>>       acpi_unmap_lsapic(pr->id);
>> -    return (0);
>> +    return ret;
>
> ... this line wouldn't need to be changed.

---
Even if cpu_down() fails, acpi_processor_remove() continues to remove the cpu.
But in this case, it should return error number since some process may run on
the cpu. If the cpu has a running process and the cpu is turned the power off,
the system may not work well.

Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com>
Reviewed-by: Toshi Kani <toshi.kani@...com>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>

---
  drivers/acpi/processor_driver.c |   16 +++++++++++-----
  1 file changed, 11 insertions(+), 5 deletions(-)

Index: linux-3.7-rc2/drivers/acpi/processor_driver.c
===================================================================
--- linux-3.7-rc2.orig/drivers/acpi/processor_driver.c	2012-10-21 04:11:32.000000000 +0900
+++ linux-3.7-rc2/drivers/acpi/processor_driver.c	2012-10-26 18:15:43.721665836 +0900
@@ -605,7 +605,7 @@ err_free_pr:
  static int acpi_processor_remove(struct acpi_device *device, int type)
  {
  	struct acpi_processor *pr = NULL;
-
+	int ret;
  
  	if (!device || !acpi_driver_data(device))
  		return -EINVAL;
@@ -616,8 +616,9 @@ static int acpi_processor_remove(struct
  		goto free;
  
  	if (type == ACPI_BUS_REMOVAL_EJECT) {
-		if (acpi_processor_handle_eject(pr))
-			return -EINVAL;
+		ret = acpi_processor_handle_eject(pr);
+		if (ret)
+			return ret;
  	}
  
  	acpi_processor_power_exit(pr);
@@ -848,8 +849,13 @@ static acpi_status acpi_processor_hotadd
  
  static int acpi_processor_handle_eject(struct acpi_processor *pr)
  {
-	if (cpu_online(pr->id))
-		cpu_down(pr->id);
+	int ret = 0;
+
+	if (cpu_online(pr->id)) {
+		ret = cpu_down(pr->id);
+		if (ret)
+			return ret;
+	}
  
  	arch_unregister_cpu(pr->id);
  	acpi_unmap_lsapic(pr->id);

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