genirq/msi: Take the per-device MSI lock before validating the control structure

Calling msi_ctrl_valid() ultimately results in calling
msi_get_device_domain(), which requires holding the device MSI lock.

However, in msi_domain_populate_irqs() the lock is taken right after having
called msi_ctrl_valid(), which is just a tad too late.

Take the lock before invoking msi_ctrl_valid().

Fixes: 4074271 ("genirq/msi: Make msi_add_simple_msi_descs() device domain aware")
Reported-by: "Russell King (Oracle)" <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Russell King (Oracle) <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/Y/Opu6ETe3ZzZ/[email protected]
Link: https://lore.kernel.org/r/[email protected]

Author: Marc Zyngier

kernel/irq/msi.c

@@ -1084,10 +1084,13 @@ int msi_domain_populate_irqs(struct irq_domain *domain, struct device *dev,
 	struct xarray *xa;
 	int ret, virq;
 
-	if (!msi_ctrl_valid(dev, &ctrl))
-		return -EINVAL;
-
 	msi_lock_descs(dev);
+
+	if (!msi_ctrl_valid(dev, &ctrl)) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+
 	ret = msi_domain_add_simple_msi_descs(dev, &ctrl);
 	if (ret)
 		goto unlock;