From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 12 Jun 2024 20:24:33 +0000 (-0400)
Subject: wfstack: make cds_wfs_empty argument const
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=c4a5a2ff58023b16d354fc4b056226c3f959566a;p=userspace-rcu.git

wfstack: make cds_wfs_empty argument const

cds_wfs_empty doesn't modify its argument. Hence, it can be
marked as `const`.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: Ie125d66296eefecfeb20a8a297b5eb04b42034a2
---

diff --git a/include/urcu/static/wfstack.h b/include/urcu/static/wfstack.h
index c46e97d..97c5192 100644
--- a/include/urcu/static/wfstack.h
+++ b/include/urcu/static/wfstack.h
@@ -106,9 +106,9 @@ static inline bool ___cds_wfs_end(void *node)
  *
  * No memory barrier is issued. No mutual exclusion is required.
  */
-static inline bool _cds_wfs_empty(cds_wfs_stack_ptr_t u_stack)
+static inline bool _cds_wfs_empty(cds_wfs_stack_const_ptr_t u_stack)
 {
-	struct __cds_wfs_stack *s = u_stack._s;
+	const struct __cds_wfs_stack *s = u_stack._s;
 
 	return ___cds_wfs_end(uatomic_load(&s->head, CMM_RELAXED));
 }
diff --git a/include/urcu/wfstack.h b/include/urcu/wfstack.h
index 38e5b6b..66d4150 100644
--- a/include/urcu/wfstack.h
+++ b/include/urcu/wfstack.h
@@ -96,6 +96,11 @@ typedef union {
 	struct __cds_wfs_stack *_s;
 	struct cds_wfs_stack *s;
 } __attribute__((__transparent_union__)) cds_wfs_stack_ptr_t;
+
+typedef union {
+	const struct __cds_wfs_stack *_s;
+	const struct cds_wfs_stack *s;
+} __attribute__((__transparent_union__)) cds_wfs_stack_const_ptr_t;
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif
@@ -167,7 +172,7 @@ extern void __cds_wfs_init(struct __cds_wfs_stack *s);
  *
  * No memory barrier is issued. No mutual exclusion is required.
  */
-extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack);
+extern bool cds_wfs_empty(cds_wfs_stack_const_ptr_t u_stack);
 
 /*
  * cds_wfs_push: push a node into the stack.
@@ -372,9 +377,25 @@ static inline cds_wfs_stack_ptr_t cds_wfs_stack_cast(struct cds_wfs_stack *s)
 	return ret;
 }
 
+static inline cds_wfs_stack_const_ptr_t cds_wfs_stack_const_cast(const struct __cds_wfs_stack *s)
+{
+	cds_wfs_stack_const_ptr_t ret = {
+		._s = s,
+	};
+	return ret;
+}
+
+static inline cds_wfs_stack_const_ptr_t cds_wfs_stack_const_cast(const struct cds_wfs_stack *s)
+{
+	cds_wfs_stack_const_ptr_t ret = {
+		.s = s,
+	};
+	return ret;
+}
+
 template<typename T> static inline bool cds_wfs_empty(T s)
 {
-	return cds_wfs_empty(cds_wfs_stack_cast(s));
+	return cds_wfs_empty(cds_wfs_stack_const_cast(s));
 }
 
 template<typename T> static inline int cds_wfs_push(T s, struct cds_wfs_node *node)
diff --git a/src/wfstack.c b/src/wfstack.c
index 8fddaec..6308a94 100644
--- a/src/wfstack.c
+++ b/src/wfstack.c
@@ -34,7 +34,7 @@ void __cds_wfs_init(struct __cds_wfs_stack *s)
 	___cds_wfs_init(s);
 }
 
-bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack)
+bool cds_wfs_empty(cds_wfs_stack_const_ptr_t u_stack)
 {
 	return _cds_wfs_empty(u_stack);
 }