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SubjectRe: [PATCH 06/11] ACPI / gsi: Add gsi_mutex to synchronize acpi_register_gsi()/acpi_unregister_gsi()
On 06/10/2015 11:58 PM, Marc Zyngier wrote:
> On 18/05/15 13:59, Hanjun Guo wrote:
>> Add a mutex for acpi_register_gsi()/acpi_unregister_gsi() to avoid
>> concurrency issues.
>>
>> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
>> ---
>> drivers/acpi/gsi.c | 17 +++++++++++++----
>> 1 file changed, 13 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/acpi/gsi.c b/drivers/acpi/gsi.c
>> index 55b5f31..ab0dcb4 100644
>> --- a/drivers/acpi/gsi.c
>> +++ b/drivers/acpi/gsi.c
>> @@ -16,6 +16,7 @@
>> enum acpi_irq_model_id acpi_irq_model;
>> /* ACPI core domian pointing to GICv2/3 core domain */
>> struct irq_domain *acpi_irq_domain __read_mostly;
>> +static DEFINE_MUTEX(gsi_mutex);
>>
>> static unsigned int acpi_gsi_get_irq_type(int trigger, int polarity)
>> {
>> @@ -73,20 +74,24 @@ int acpi_register_gsi(struct device *dev, u32 gsi, int trigger,
>> int irq;
>> unsigned int irq_type = acpi_gsi_get_irq_type(trigger, polarity);
>>
>> + mutex_lock(&gsi_mutex);
>> irq = irq_find_mapping(acpi_irq_domain, gsi);
>> if (irq > 0)
>> - return irq;
>> + goto out;
>>
>> irq = irq_domain_alloc_irqs(acpi_irq_domain, 1, dev_to_node(dev),
>> &gsi);
>> if (irq <= 0)
>> - return -EINVAL;
>> + goto out;
>>
>> /* Set irq type if specified and different than the current one */
>> if (irq_type != IRQ_TYPE_NONE &&
>> irq_type != irq_get_trigger_type(irq))
>> irq_set_irq_type(irq, irq_type);
>> - return irq;
>> +
>> +out:
>> + mutex_unlock(&gsi_mutex);
>> + return irq > 0 ? irq : -EINVAL;
>> }
>> EXPORT_SYMBOL_GPL(acpi_register_gsi);
>>
>> @@ -96,8 +101,12 @@ EXPORT_SYMBOL_GPL(acpi_register_gsi);
>> */
>> void acpi_unregister_gsi(u32 gsi)
>> {
>> - int irq = irq_find_mapping(acpi_irq_domain, gsi);
>> + int irq;
>> +
>> + mutex_lock(&gsi_mutex);
>> + irq = irq_find_mapping(acpi_irq_domain, gsi);
>>
>> irq_dispose_mapping(irq);
>> + mutex_unlock(&gsi_mutex);
>> }
>> EXPORT_SYMBOL_GPL(acpi_unregister_gsi);
>>
>
> Can you point out why we need this locking? The rest of the kernel seems
> to live without it pretty well. And if we really have an issue, I'd

Hmm, I'm not so sure, I will look deep into that and come back later.

> prefer seeing it fixed in the core code rather than in something that is
> very much firmware-specific.

I agree if there are real issues.

Thanks
Hanjun


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