linux-kernel - [RFC 12/14] task_stack.h: Clean-up stack_not

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Date: Mon, 11 Mar 2024 16:46:36 +0000
From: Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: [RFC 12/14] task_stack.h: Clean-up stack_not_used() implementation

Inside small stack_not_used() function there are several ifdefs for
stack growing-up vs. regular versions. Instead just implement this
function two times, one for growing-up and another regular.

This is needed, because there will be a third implementation of this
function for dynamic stacks.

Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
---
 include/linux/sched/task_stack.h | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index 4934bfd65ad1..396d5418ae32 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -135,25 +135,30 @@ static inline int object_is_on_stack(const void *obj)
 extern void thread_stack_cache_init(void);
 
 #ifdef CONFIG_DEBUG_STACK_USAGE
+#ifdef CONFIG_STACK_GROWSUP
 static inline unsigned long stack_not_used(struct task_struct *p)
 {
 	unsigned long *n = end_of_stack(p);
 
-	do { 	/* Skip over canary */
-# ifdef CONFIG_STACK_GROWSUP
+	do {	/* Skip over canary */
 		n--;
-# else
-		n++;
-# endif
 	} while (!*n);
 
-# ifdef CONFIG_STACK_GROWSUP
 	return (unsigned long)end_of_stack(p) - (unsigned long)n;
-# else
+}
+#else /* !CONFIG_STACK_GROWSUP */
+static inline unsigned long stack_not_used(struct task_struct *p)
+{
+	unsigned long *n = end_of_stack(p);
+
+	do {	/* Skip over canary */
+		n++;
+	} while (!*n);
+
 	return (unsigned long)n - (unsigned long)end_of_stack(p);
-# endif
 }
-#endif
+#endif /* CONFIG_STACK_GROWSUP */
+#endif /* CONFIG_DEBUG_STACK_USAGE */
 
 static inline int kstack_end(void *addr)
 {
-- 
2.44.0.278.ge034bb2e1d-goog