Is timer callback function preemptable in softirq?

[kaizsv]

pikoRT/kernel/time.c

Line 21 in 8089111

sched_enqueue(timer->owner);

Softirq is a thread like main or idle in Piko/RT. Is softirq preemptable or tasklet preemptable?

For example, the callback function of msleep will call sched_enqueue. It first adds a thread at the tail of the queue, and then sets the priority level at the unsigned integer, map. If PendSV preempts at the first step and swap the active and expired runqueue because the value of map of active runqueue is zero. This will cause an error.

The GDB says the systick can preempt the softirq, but I can not specify the interrupt point at the softirq. I am wondering, whether the callback function (msleep_callback) is preemptable at the execution time?