On 12/09/2019 10:44, Sverdlin, Alexander (Nokia - DE/Ulm) wrote:

From: Alexander Sverdlin alexander.sverdlin@nokia.com

irq_domain_associate() is the only place where irq_find_mapping() can be used reliably (under irq_domain_mutex) to make a decision if the mapping shall be created or not. Other calls to irq_find_mapping() (not under any lock) cannot be used for this purpose and lead to race conditions in particular inside irq_create_mapping().

Give the callers of irq_domain_associate() an ability to detect existing domain reliably by examining the return value.

Cc: stable@vger.kernel.org Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com

---

kernel/irq/irqdomain.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 3078d0e..7bc07b6 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -532,6 +532,7 @@ 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);

• unsigned int eirq; int ret;

if (WARN(hwirq >= domain->hwirq_max, @@ -543,6 +544,16 @@ int irq_domain_associate(struct irq_domain *domain, unsigned int virq, return -EINVAL; mutex_lock(&irq_domain_mutex);

• /* Check if mapping already exists */
• eirq = irq_find_mapping(domain, hwirq);
• if (eirq) {

nit: Just have

if (irq_find_mapping(...)) {

and get rid the extra variable, given that it's not used for anything.

• mutex_unlock(&irq_domain_mutex);
  

• pr_debug("%s: conflicting mapping for hwirq 0x%x\n",
  

• 	 domain->name, (int)hwirq);
  

• return -EBUSY;
  

I'm overall OK with this, although I'd rather we return -EEXIST rather than -EBUSY.

• }
• irq_data->hwirq = hwirq; irq_data->domain = domain; if (domain->ops->map) {

Thanks,

M.