linux-kernel - [PATCH v6 3/3] task_stack: uninline stack_not

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Message-ID: <20240730150158.832783-4-pasha.tatashin@soleen.com>
Date: Tue, 30 Jul 2024 15:01:58 +0000
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: akpm@...ux-foundation.org,
	jpoimboe@...nel.org,
	pasha.tatashin@...een.com,
	kent.overstreet@...ux.dev,
	peterz@...radead.org,
	nphamcs@...il.com,
	cerasuolodomenico@...il.com,
	surenb@...gle.com,
	lizhijian@...itsu.com,
	willy@...radead.org,
	shakeel.butt@...ux.dev,
	vbabka@...e.cz,
	ziy@...dia.com,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	yosryahmed@...gle.com
Subject: [PATCH v6 3/3] task_stack: uninline stack_not_used

Given that stack_not_used() is not performance critical function
uninline it.

Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
Acked-by: Shakeel Butt <shakeel.butt@...ux.dev>
---
 include/linux/sched/task_stack.h | 18 +++---------------
 kernel/exit.c                    | 19 +++++++++++++++++++
 kernel/sched/core.c              |  4 +---
 3 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index ccd72b978e1f..bf10bdb487dd 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -95,23 +95,11 @@ static inline int object_is_on_stack(const void *obj)
 extern void thread_stack_cache_init(void);
 
 #ifdef CONFIG_DEBUG_STACK_USAGE
+unsigned long stack_not_used(struct task_struct *p);
+#else
 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
-		n--;
-# else
-		n++;
-# endif
-	} while (!*n);
-
-# ifdef CONFIG_STACK_GROWSUP
-	return (unsigned long)end_of_stack(p) - (unsigned long)n;
-# else
-	return (unsigned long)n - (unsigned long)end_of_stack(p);
-# endif
+	return 0;
 }
 #endif
 extern void set_task_stack_end_magic(struct task_struct *tsk);
diff --git a/kernel/exit.c b/kernel/exit.c
index 64bfc2bae55b..45085a0e7c16 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -778,6 +778,25 @@ static void exit_notify(struct task_struct *tsk, int group_dead)
 }
 
 #ifdef CONFIG_DEBUG_STACK_USAGE
+unsigned long stack_not_used(struct task_struct *p)
+{
+	unsigned long *n = end_of_stack(p);
+
+	do {	/* Skip over canary */
+# ifdef CONFIG_STACK_GROWSUP
+		n--;
+# else
+		n++;
+# endif
+	} while (!*n);
+
+# ifdef CONFIG_STACK_GROWSUP
+	return (unsigned long)end_of_stack(p) - (unsigned long)n;
+# else
+	return (unsigned long)n - (unsigned long)end_of_stack(p);
+# endif
+}
+
 /* Count the maximum pages reached in kernel stacks */
 static inline void kstack_histogram(unsigned long used_stack)
 {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a9f655025607..b275f4f27e3c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7405,7 +7405,7 @@ EXPORT_SYMBOL(io_schedule);
 
 void sched_show_task(struct task_struct *p)
 {
-	unsigned long free = 0;
+	unsigned long free;
 	int ppid;
 
 	if (!try_get_task_stack(p))
@@ -7415,9 +7415,7 @@ void sched_show_task(struct task_struct *p)
 
 	if (task_is_running(p))
 		pr_cont("  running task    ");
-#ifdef CONFIG_DEBUG_STACK_USAGE
 	free = stack_not_used(p);
-#endif
 	ppid = 0;
 	rcu_read_lock();
 	if (pid_alive(p))
-- 
2.46.0.rc1.232.g9752f9e123-goog