lib: Add epoch-based SMR

sched/core.c

@@ -4,7 +4,9 @@
 #include <zinnia/assert.h>
 #include <zinnia/atomic.h>
 #include <zinnia/errno.h>
+#include <zinnia/irq.h>
 #include <zinnia/park.h>
+#include <zinnia/percpu.h>
 #include <zinnia/process.h>
 #include <zinnia/sched.h>
 #include <zinnia/spin.h>
@@ -163,3 +165,16 @@ void sched_sleep_until(uint64_t deadline_ns) {
     const uint8_t key = 0;
     park_timeout(&key, nullptr, nullptr, nullptr, 0, &deadline_ns);
 }
+
+void sched_preempt_disable() {
+    arch_sched_preempt_disable();
+}
+
+void sched_preempt_enable() {
+    if (!arch_sched_preempt_enable())
+        return;
+    struct scheduler* sched = &percpu_get()->sched;
+    if ((sched->owe_preempt || sched->need_resched) && percpu_ref(irq_data)->depth == 0 && irq_get_state() &&
+        sched->current)
+        sched_reschedule(sched);
+}