kernel: sys_workq: add k_is_in_sys_work API

Add k_is_in_sys_work() API which returns true if the thread context
is the system workqueue thread and the thread is currently servicing
a work item. Useful for checking if blocking is safe or required in
the case of calling an API which uses the system work queue
internally.

Signed-off-by: Bjarki Arge Andreasen <[email protected]>

Author: bjarki-andreasen

include/zephyr/kernel.h

@@ -1181,6 +1181,19 @@ void k_thread_time_slice_set(struct k_thread *th, int32_t slice_ticks,
  */
 bool k_is_in_isr(void);
 
+/**
+ * @brief Determine if code is running from system work item
+ *
+ * This routine allows the caller to customize its actions, depending on
+ * whether it is running fom a system work item.
+ *
+ * @funcprops \isr_ok
+ *
+ * @return false if noit invoked from a system work item.
+ * @return true if invoked from a system work item.
+ */
+bool k_is_in_sys_work(void);
+
 /**
  * @brief Determine if code is running in a preemptible thread.
  *

kernel/work.c

@@ -1175,3 +1175,9 @@ bool k_work_flush_delayable(struct k_work_delayable *dwork,
 }
 
 #endif /* CONFIG_SYS_CLOCK_EXISTS */
+
+bool k_is_in_sys_work(void)
+{
+	return k_current_get() == k_work_queue_thread_get(&k_sys_work_q) &&
+	       flag_test(&k_sys_work_q.flags, K_WORK_QUEUE_BUSY_BIT);
+}