From d5409daa794d9384555eb540e3baaaa8b6a8600c Mon Sep 17 00:00:00 2001
From: Vojtech Horky <vojtech.horky@gmail.com>
Date: Thu, 13 Jul 2023 22:05:54 +0200
Subject: [PATCH] C++: mutex::init should be constexpr

---
 uspace/lib/c/generic/thread/fibril_synch.c         |  7 -------
 uspace/lib/c/include/adt/list.h                    |  2 +-
 uspace/lib/c/include/fibril_synch.h                | 14 +++++++++++++-
 uspace/lib/cpp/include/__bits/thread/threading.hpp |  2 +-
 4 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/uspace/lib/c/generic/thread/fibril_synch.c b/uspace/lib/c/generic/thread/fibril_synch.c
index 54a05e925..2326d001a 100644
--- a/uspace/lib/c/generic/thread/fibril_synch.c
+++ b/uspace/lib/c/generic/thread/fibril_synch.c
@@ -161,13 +161,6 @@ static void check_for_deadlock(fibril_owner_info_t *oi)
 	check_fibril_for_deadlock(oi, fibril_self());
 }
 
-void fibril_mutex_initialize(fibril_mutex_t *fm)
-{
-	fm->oi.owned_by = NULL;
-	fm->counter = 1;
-	list_initialize(&fm->waiters);
-}
-
 void fibril_mutex_lock(fibril_mutex_t *fm)
 {
 	fibril_t *f = (fibril_t *) fibril_get_id();
diff --git a/uspace/lib/c/include/adt/list.h b/uspace/lib/c/include/adt/list.h
index 0c8cbf965..9013a6380 100644
--- a/uspace/lib/c/include/adt/list.h
+++ b/uspace/lib/c/include/adt/list.h
@@ -182,7 +182,7 @@ _NO_TRACE static inline void link_initialize(link_t *link)
  * @param list Pointer to list_t structure.
  *
  */
-_NO_TRACE static inline void list_initialize(list_t *list)
+_NO_TRACE static inline __CONSTEXPR void list_initialize(list_t *list)
 {
 	list->head.prev = &list->head;
 	list->head.next = &list->head;
diff --git a/uspace/lib/c/include/fibril_synch.h b/uspace/lib/c/include/fibril_synch.h
index db374ed4a..fc32aa13d 100644
--- a/uspace/lib/c/include/fibril_synch.h
+++ b/uspace/lib/c/include/fibril_synch.h
@@ -152,7 +152,19 @@ typedef struct {
 extern void __fibril_synch_init(void);
 extern void __fibril_synch_fini(void);
 
-extern void fibril_mutex_initialize(fibril_mutex_t *);
+/** Initialize fibril mutex.
+ *
+ * Kept as in-line to allow constexpr marker for C++ library where this
+ * is used by C++ mutex type (list initialization are two assignments
+ * so it is actually reasonable to have this inlined).
+ */
+static inline __CONSTEXPR void fibril_mutex_initialize(fibril_mutex_t *fm)
+{
+	fm->oi.owned_by = NULL;
+	fm->counter = 1;
+	list_initialize(&fm->waiters);
+}
+
 extern void fibril_mutex_lock(fibril_mutex_t *);
 extern bool fibril_mutex_trylock(fibril_mutex_t *);
 extern void fibril_mutex_unlock(fibril_mutex_t *);
diff --git a/uspace/lib/cpp/include/__bits/thread/threading.hpp b/uspace/lib/cpp/include/__bits/thread/threading.hpp
index 76de59184..020800775 100644
--- a/uspace/lib/cpp/include/__bits/thread/threading.hpp
+++ b/uspace/lib/cpp/include/__bits/thread/threading.hpp
@@ -86,7 +86,7 @@ namespace std::aux
 
         struct mutex
         {
-            static void init(mutex_type& mtx)
+            static constexpr void init(mutex_type& mtx)
             {
                 ::helenos::fibril_mutex_initialize(&mtx);
             }
-- 
2.11.4.GIT