hujun260 commented on code in PR #13349:
URL: https://github.com/apache/nuttx/pull/13349#discussion_r1765042687
##########
sched/irq/irq_csection.c:
##########
@@ -345,6 +345,26 @@ irqstate_t enter_critical_section(void)
}
else
{
+ /* CHECK IRQ
+ *
+ * After the OS starts, in the thread context,
+ * we must ensure that the interrupt is not masked
+ * when first enters the critical section.
+ * Otherwise, at this time when another CPU issues a pause
+ * interrupt to the current CPU, it can lead to a deadlock.
+ *
+ * During the vela os startup phase, interrupts are masked until
+ * the interrupt initialization function (irq_initialize) is
Review Comment:
The enter_critical_section relies on irq being enabled in its normal context
due to its specific strategy of reenable irq to respond to up_cpu_pause when
the lock cannot be acquired immediately.
However, spin_lock_irqsave disabled irq make the strategy employed by
enter_critical_section faild,
potentially leading to a deadlock situation."
cpu0<br/><br/><br/><br/><br/> cpu1
enter_critical_section
up_cpu_pause(will wait until succed)
spin_lock_irqsave(NULL);
enter_critical_section(**deadlock**)
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