Re: [PATCH 2/2] ACPI: AGDI: Add driver for Arm Generic Diagnostic Dump and Reset device

[ilkka]

Hi,

Thanks for reviewing the patch

On Thu, 9 Dec 2021, Russell King (Oracle) wrote:
> Hi,
>
> On Thu, Dec 02, 2021 at 06:43:11PM -0800, Ilkka Koskinen wrote:
> > +static int __init agdi_init(void)
> > +{
> > +	int ret;
> > +	acpi_status status;
> > +	struct acpi_table_agdi *agdi_table;
> > +	struct agdi_data *pdata;
> > +	struct platform_device *pdev;
> > +
> > +	if (acpi_disabled)
> > +		return 0;
> > +
> > +	status = acpi_get_table(ACPI_SIG_AGDI, 0,
> > +				(struct acpi_table_header **) &agdi_table);
> > +	if (ACPI_FAILURE(status))
> > +		return -ENODEV;
> > +
> > +	pdata = kzalloc(sizeof(*pdata), GFP_ATOMIC);
>
> Why does this need to be GFP_ATOMIC? Also, struct agdi_data is a single
> int in size, why do you need to kzalloc() it?

There's no reason for that. It should obviously be GFP_KERNEL

> > +	if (!pdata) {
> > +		ret = -ENOMEM;
> > +		goto err_put_table;
> > +	}
> > +
> > +	if (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE) {
> > +		pr_warn("Interrupt signaling is not supported");
> > +		ret = -ENODEV;
> > +		goto err_free_pdata;
> > +	}
> > +
> > +	pdata->sdei_event = agdi_table->sdei_event;
> > +
> > +	pdev = platform_device_register_data(NULL, "agdi", 0, pdata, sizeof(*pdata));
>
> platform_device_register_data() uses kmemdup() internally with the
> platform data, meaning it takes a copy of the platform data. There is
> no need for the pdata allocation to persist past this point. Hence,
> given that it is a single int in size, you may as well put
> "struct agdi_data" on the stack.

I somehow missed kmemdup() part. I remove the allocation and move pdata to 
the stack instead.

Thanks,
Ilkka


> Thanks.
>
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