linux-kernel - Re: [PATCH 4/8] donot allow to eject the memory device if it is being used

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Date:	Thu, 28 Jun 2012 10:01:26 +0800
From:	Wen Congyang <wency@...fujitsu.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Yasuaki ISIMATU <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH 4/8] donot allow to eject the memory device if it is being
 used

At 06/27/2012 12:21 PM, David Rientjes Wrote:
> On Tue, 26 Jun 2012, Wen Congyang wrote:
> 
>> diff --git a/drivers/acpi/acpi_memhotplug.c b/drivers/acpi/acpi_memhotplug.c
>> index a325bb9..2e5d5ab 100644
>> --- a/drivers/acpi/acpi_memhotplug.c
>> +++ b/drivers/acpi/acpi_memhotplug.c
>> @@ -78,6 +78,7 @@ struct acpi_memory_info {
>>  	unsigned short caching;	/* memory cache attribute */
>>  	unsigned short write_protect;	/* memory read/write attribute */
>>  	unsigned int enabled:1;
>> +	unsigned int failed:1;
>>  };
>>  
>>  struct acpi_memory_device {
>> @@ -251,9 +252,19 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
>>  			node = memory_add_physaddr_to_nid(info->start_addr);
>>  
>>  		result = add_memory(node, info->start_addr, info->length);
>> -		if (result)
>> +
>> +		/*
>> +		 * If the memory block has been used by the kernel, add_memory()
>> +		 * returns -EEXIST. If add_memory() returns the other error, it
>> +		 * means that this memory block is not used by the kernel.
>> +		 */
>> +		if (result && result != -EEXIST) {
>> +			info->failed = 1;
>>  			continue;
>> -		info->enabled = 1;
>> +		}
>> +
>> +		if (!result)
>> +			info->enabled = 1;
>>  		num_enabled++;
>>  	}
>>  	if (!num_enabled) {
> 
> num_enabled should only be incremented for result == 0.
> 

If num_enabled is not incremented for result == -EEXIST, this device is not
managed by this module, and it is not able to be hot removed. Another problem
is the user will see a strange message: add_memory failed

Thanks
Wen Congyang
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