Add verify_lock() function.

Allows for annotations such as
xassert(verify_lock(CONFIG_LOCK, READ_LOCK));
to ensure that the calling thread has the correct locks in
place to head off potential race conditions / corruption.

src/slurmctld/locks.c

@@ -102,6 +102,11 @@ static bool _clear_locks(slurmctld_lock_t lock_levels)
 
 	return true;
 }
+
+extern bool verify_lock(lock_datatype_t datatype, lock_level_t level)
+{
+	return (((lock_level_t *) &thread_locks)[datatype] >= level);
+}
 #endif
 
 /* init_locks - create locks used for slurmctld data structure access

src/slurmctld/locks.h

@@ -91,6 +91,8 @@
 #ifndef _SLURMCTLD_LOCKS_H
 #define _SLURMCTLD_LOCKS_H
 
+#include <stdbool.h>
+
 /* levels of locking required for each data structure */
 typedef enum {
 	NO_LOCK,
@@ -125,6 +127,10 @@ typedef enum {
 	ENTITY_COUNT
 }	lock_datatype_t;
 
+#ifndef NDEBUG
+extern bool verify_lock(lock_datatype_t datatype, lock_level_t level);
+#endif
+
 #define read_lock(data_type)		(data_type * 4 + 0)
 #define write_lock(data_type)		(data_type * 4 + 1)
 #define write_wait_lock(data_type)	(data_type * 4 + 2)