Re: [PATCH v5 06/19] irqdomain: Fix mapping-creation race

On Thu, 09 Feb 2023 13:23:10 +0000, Johan Hovold johan+linaro@kernel.org wrote:

Parallel probing of devices that share interrupts (e.g. when a driver uses asynchronous probing) can currently result in two mappings for the same hardware interrupt to be created due to missing serialisation.

Make sure to hold the irq_domain_mutex when creating mappings so that looking for an existing mapping before creating a new one is done atomically.

Fixes: 765230b5f084 ("driver-core: add asynchronous probing support for drivers") Fixes: b62b2cf5759b ("irqdomain: Fix handling of type settings for existing mappings") Link: https://lore.kernel.org/r/YuJXMHoT4ijUxnRb@hovoldconsulting.com Cc: stable@vger.kernel.org # 4.8 Cc: Dmitry Torokhov dtor@chromium.org Cc: Jon Hunter jonathanh@nvidia.com Tested-by: Hsin-Yi Wang hsinyi@chromium.org Tested-by: Mark-PK Tsai mark-pk.tsai@mediatek.com Signed-off-by: Johan Hovold johan+linaro@kernel.org

---

kernel/irq/irqdomain.c | 55 ++++++++++++++++++++++++++++++------------ 1 file changed, 40 insertions(+), 15 deletions(-)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 7b57949bc79c..1ddb01bd49a4 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -25,6 +25,9 @@ static DEFINE_MUTEX(irq_domain_mutex); static struct irq_domain *irq_default_domain; +static int irq_domain_alloc_irqs_locked(struct irq_domain *domain, int irq_base,

• 			unsigned int nr_irqs, int node, void *arg,
  

• 			bool realloc, const struct irq_affinity_desc *affinity);
  

static void irq_domain_check_hierarchy(struct irq_domain *domain); struct irqchip_fwid { @@ -682,9 +685,9 @@ unsigned int irq_create_direct_mapping(struct irq_domain *domain) EXPORT_SYMBOL_GPL(irq_create_direct_mapping); #endif -static unsigned int __irq_create_mapping_affinity(struct irq_domain *domain,

• 				  irq_hw_number_t hwirq,
  

• 				  const struct irq_affinity_desc *affinity)
  

+static unsigned int irq_create_mapping_affinity_locked(struct irq_domain *domain,

• 				       irq_hw_number_t hwirq,
  

• 				       const struct irq_affinity_desc *affinity)
  

{ struct device_node *of_node = irq_domain_get_of_node(domain); int virq; @@ -699,7 +702,7 @@ static unsigned int __irq_create_mapping_affinity(struct irq_domain *domain, return 0; }

• if (irq_domain_associate(domain, virq, hwirq)) {

• if (irq_domain_associate_locked(domain, virq, hwirq)) { irq_free_desc(virq); return 0; }

@@ -735,14 +738,20 @@ unsigned int irq_create_mapping_affinity(struct irq_domain *domain, return 0; }

• mutex_lock(&irq_domain_mutex);
• /* Check if mapping already exists */ virq = irq_find_mapping(domain, hwirq); if (virq) { pr_debug("existing mapping on virq %d\n", virq);

• return virq;
  

• goto out;
  

  }

• return __irq_create_mapping_affinity(domain, hwirq, affinity);

• virq = irq_create_mapping_affinity_locked(domain, hwirq, affinity);

+out:

• mutex_unlock(&irq_domain_mutex);
• return virq;

} EXPORT_SYMBOL_GPL(irq_create_mapping_affinity); @@ -809,6 +818,8 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec) if (WARN_ON(type & ~IRQ_TYPE_SENSE_MASK)) type &= IRQ_TYPE_SENSE_MASK;

• mutex_lock(&irq_domain_mutex);
• /*
  • If we've already configured this interrupt,
  • don't do it again, or hell will break loose.

@@ -821,7 +832,7 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec) * interrupt number. */ if (type == IRQ_TYPE_NONE || type == irq_get_trigger_type(virq))

• 	return virq;
  

• 	goto out;
  

/* * If the trigger type has not been set yet, then set @@ -830,36 +841,43 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec) if (irq_get_trigger_type(virq) == IRQ_TYPE_NONE) { irq_data = irq_get_irq_data(virq); if (!irq_data)

• 		return 0;
  

• 		goto err;
  

irqd_set_trigger_type(irq_data, type);

• 	return virq;
  

• 	goto out;
  

  }

pr_warn("type mismatch, failed to map hwirq-%lu for %s!\n", hwirq, of_node_full_name(to_of_node(fwspec->fwnode)));

• return 0;
  

• goto err;
  

  }

if (irq_domain_is_hierarchy(domain)) {

• virq = irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, fwspec);
  

• virq = irq_domain_alloc_irqs_locked(domain, -1, 1, NUMA_NO_NODE,
  

• 				    fwspec, false, NULL);
  

  if (virq <= 0)

• 	return 0;
  

• 	goto err;
  

  } else { /* Create mapping */

• virq = __irq_create_mapping_affinity(domain, hwirq, NULL);
  

• virq = irq_create_mapping_affinity_locked(domain, hwirq, NULL);
  

  if (!virq)

• 	return virq;
  

• 	goto err;
  

  }

irq_data = irq_get_irq_data(virq); if (WARN_ON(!irq_data))

• return 0;
  

• goto err;
  

/* Store trigger type */ irqd_set_trigger_type(irq_data, type); +out:

• mutex_unlock(&irq_domain_mutex);

return virq; +err:

• mutex_unlock(&irq_domain_mutex);
• return 0;

nit: it'd look better if we had a single exit path with the unlock, setting virq to 0 on failure. Not a big deal, as this can be tidied up when applied.

Thanks,

M.