2023-01-16 15:23:36

by Johan Hovold

Subject: [PATCH v4 04/19] irqdomain: Fix association race

The sanity check for an already mapped virq was done outside of the
irq_domain_mutex-protected section which meant that an (unlikely) racing
association may not be detected.

Fix this by factoring out the association implementation, which will
also be used in follow-on changes to rework the locking.

Fixes: ddaf144c61da ("irqdomain: Refactor irq_domain_associate_many()")
Tested-by: Hsin-Yi Wang <[email protected]>
Tested-by: Mark-PK Tsai <[email protected]>
Signed-off-by: Johan Hovold <[email protected]>
---
kernel/irq/irqdomain.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index dfd60bd49109..b2087f55a1ac 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -558,8 +558,8 @@ static void irq_domain_disassociate(struct irq_domain *domain, unsigned int irq)
irq_domain_clear_mapping(domain, hwirq);
}

-int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
- irq_hw_number_t hwirq)
+static int __irq_domain_associate(struct irq_domain *domain, unsigned int virq,
+ irq_hw_number_t hwirq)
{
struct irq_data *irq_data = irq_get_irq_data(virq);
int ret;
@@ -572,7 +572,6 @@ int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
if (WARN(irq_data->domain, "error: virq%i is already associated", virq))
return -EINVAL;

- mutex_lock(&irq_domain_mutex);
irq_data->hwirq = hwirq;
irq_data->domain = domain;
if (domain->ops->map) {
@@ -589,19 +588,29 @@ int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
}
irq_data->domain = NULL;
irq_data->hwirq = 0;
- mutex_unlock(&irq_domain_mutex);
return ret;
}
}

domain->mapcount++;
irq_domain_set_mapping(domain, hwirq, irq_data);
- mutex_unlock(&irq_domain_mutex);

irq_clear_status_flags(virq, IRQ_NOREQUEST);

return 0;
}
+
+int irq_domain_associate(struct irq_domain *domain, unsigned int virq,
+ irq_hw_number_t hwirq)
+{
+ int ret;
+
+ mutex_lock(&irq_domain_mutex);
+ ret = __irq_domain_associate(domain, virq, hwirq);
+ mutex_unlock(&irq_domain_mutex);
+
+ return ret;
+}
EXPORT_SYMBOL_GPL(irq_domain_associate);

void irq_domain_associate_many(struct irq_domain *domain, unsigned int irq_base,
--
2.38.2

2023-01-17 23:47:10

by Thomas Gleixner

Subject: Re: [PATCH v4 04/19] irqdomain: Fix association race

On Mon, Jan 16 2023 at 14:50, Johan Hovold wrote:
> The sanity check for an already mapped virq was done outside of the

s/was/is/

> irq_domain_mutex-protected section which meant that an (unlikely) racing

s/meant/means/

> association may not be detected.

You describe the status quo and then correctly what the fix is:

> Fix this by factoring out the association implementation, which will
> also be used in follow-on changes to rework the locking.

Otherwise your fix fixes something which existed in the past, no?

Thanks,

tglx