diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index dc8b35f2d5458368afc2270cb16470c82e73059d..44fc505815d6eb589572815a1eb6bbcc0bab0e2c 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -96,7 +96,8 @@ EXPORT_SYMBOL(synchronize_hardirq);
  *	to complete before returning. If you use this function while
  *	holding a resource the IRQ handler may need you will deadlock.
  *
- *	This function may be called - with care - from IRQ context.
+ *	Can only be called from preemptible code as it might sleep when
+ *	an interrupt thread is associated to @irq.
  */
 void synchronize_irq(unsigned int irq)
 {