linux-kernel - Re: [PATCH] vfio/platform: Remove the ACPI buffer memory to fix memory leak

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Date:   Wed, 30 Nov 2022 09:20:13 +0800
From:   Hanjun Guo <guohanjun@...wei.com>
To:     Alex Williamson <alex.williamson@...hat.com>
CC:     Eric Auger <eric.auger@...hat.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Sinan Kaya <okaya@...eaurora.org>
Subject: Re: [PATCH] vfio/platform: Remove the ACPI buffer memory to fix
 memory leak

On 2022/11/30 3:52, Alex Williamson wrote:
> On Tue, 22 Nov 2022 19:29:58 +0800
> Hanjun Guo <guohanjun@...wei.com> wrote:
> 
>> The ACPI buffer memory (buffer.pointer) returned by acpi_evaluate_object()
>> is not used after the call of _RST method, so it leads to memory leak.
>>
>> For the calling of ACPI _RST method, we don't need to pass a buffer
>> for acpi_evaluate_object(), we can just pass NULL and remove the ACPI
>> buffer memory in vfio_platform_acpi_call_reset(), then we don't need to
>> free the memory and no memory leak.
>>
>> Fixes: d30daa33ec1d ("vfio: platform: call _RST method when using ACPI")
>> Signed-off-by: Hanjun Guo <guohanjun@...wei.com>
>> ---
>>   drivers/vfio/platform/vfio_platform_common.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
>> index 55dc4f4..1a0a238 100644
>> --- a/drivers/vfio/platform/vfio_platform_common.c
>> +++ b/drivers/vfio/platform/vfio_platform_common.c
>> @@ -72,12 +72,11 @@ static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
>>   				  const char **extra_dbg)
>>   {
>>   #ifdef CONFIG_ACPI
>> -	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
>>   	struct device *dev = vdev->device;
>>   	acpi_handle handle = ACPI_HANDLE(dev);
>>   	acpi_status acpi_ret;
>>   
>> -	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
>> +	acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, NULL);
>>   	if (ACPI_FAILURE(acpi_ret)) {
>>   		if (extra_dbg)
>>   			*extra_dbg = acpi_format_exception(acpi_ret);
> 
> An identical change was already posted and accepted into the vfio next
> branch, see:
> 
> https://lore.kernel.org/all/20221018152825.891032-1-rafaelmendsr@gmail.com/
> 
> In linux-next as:
> 
> e67e070632a6 ("vfio: platform: Do not pass return buffer to ACPI _RST method")

Thanks, I missed this patch, please drop this one.

Thanks
Hanjun