[PATCH 37/53] sched/headers: Move task-stack related APIs from to

Ingo Molnar
2017-02-08T20:43:07Z

Split out the task->stack related functionality, which is not really
part of the core scheduler APIs.

Only keep task_thread_info() because it's used by sched.h.

Update the code that uses those facilities.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
include/linux/sched.h | 115 +++++------------------------------------------------------
include/linux/sched/task_stack.h | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 113 insertions(+), 106 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4a8bceb9ca75..ff02889f092c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1446,6 +1446,15 @@ union thread_union {
unsigned long stack[THREAD_SIZE/sizeof(long)];
};

+#ifdef CONFIG_THREAD_INFO_IN_TASK
+static inline struct thread_info *task_thread_info(struct task_struct *task)
+{
+ return &task->thread_info;
+}
+#elif !defined(__HAVE_THREAD_FUNCTIONS)
+# define task_thread_info(task) ((struct thread_info *)(task)->stack)
+#endif
+
#ifndef __HAVE_ARCH_KSTACK_END
static inline int kstack_end(void *addr)
{
@@ -1536,112 +1545,6 @@ static inline void task_unlock(struct task_struct *p)
spin_unlock(&p->alloc_lock);
}

-#ifdef CONFIG_THREAD_INFO_IN_TASK
-
-static inline struct thread_info *task_thread_info(struct task_struct *task)
-{
- return &task->thread_info;
-}
-
-/*
- * When accessing the stack of a non-current task that might exit, use
- * try_get_task_stack() instead. task_stack_page will return a pointer
- * that could get freed out from under you.
- */
-static inline void *task_stack_page(const struct task_struct *task)
-{
- return task->stack;
-}
-
-#define setup_thread_stack(new,old) do { } while(0)
-
-static inline unsigned long *end_of_stack(const struct task_struct *task)
-{
- return task->stack;
-}
-
-#elif !defined(__HAVE_THREAD_FUNCTIONS)
-
-#define task_thread_info(task) ((struct thread_info *)(task)->stack)
-#define task_stack_page(task) ((void *)(task)->stack)
-
-static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
-{
- *task_thread_info(p) = *task_thread_info(org);
- task_thread_info(p)->task = p;
-}
-
-/*
- * Return the address of the last usable long on the stack.
- *
- * When the stack grows down, this is just above the thread
- * info struct. Going any lower will corrupt the threadinfo.
- *
- * When the stack grows up, this is the highest address.
- * Beyond that position, we corrupt data on the next page.
- */
-static inline unsigned long *end_of_stack(struct task_struct *p)
-{
-#ifdef CONFIG_STACK_GROWSUP
- return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
-#else
- return (unsigned long *)(task_thread_info(p) + 1);
-#endif
-}
-
-#endif
-
-#ifdef CONFIG_THREAD_INFO_IN_TASK
-static inline void *try_get_task_stack(struct task_struct *tsk)
-{
- return atomic_inc_not_zero(&tsk->stack_refcount) ?
- task_stack_page(tsk) : NULL;
-}
-
-extern void put_task_stack(struct task_struct *tsk);
-#else
-static inline void *try_get_task_stack(struct task_struct *tsk)
-{
- return task_stack_page(tsk);
-}
-
-static inline void put_task_stack(struct task_struct *tsk) {}
-#endif
-
-#define task_stack_end_corrupted(task) \
- (*(end_of_stack(task)) != STACK_END_MAGIC)
-
-static inline int object_is_on_stack(void *obj)
-{
- void *stack = task_stack_page(current);
-
- return (obj >= stack) && (obj < (stack + THREAD_SIZE));
-}
-
-extern void thread_stack_cache_init(void);
-
-#ifdef CONFIG_DEBUG_STACK_USAGE
-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
-}
-#endif
-extern void set_task_stack_end_magic(struct task_struct *tsk);
-
/* set thread flags in other task's structures
* - see asm/thread_info.h for TIF_xxxx flags available
*/
diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index d2d578e85f7d..aaa5c2a6a0e9 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -1,7 +1,111 @@
#ifndef _LINUX_SCHED_TASK_STACK_H
#define _LINUX_SCHED_TASK_STACK_H

+/*
+ * task->stack (kernel stack) handling interfaces:
+ */
+
#include <linux/sched.h>
#include <linux/magic.h>

+#ifdef CONFIG_THREAD_INFO_IN_TASK
+
+/*
+ * When accessing the stack of a non-current task that might exit, use
+ * try_get_task_stack() instead. task_stack_page will return a pointer
+ * that could get freed out from under you.
+ */
+static inline void *task_stack_page(const struct task_struct *task)
+{
+ return task->stack;
+}
+
+#define setup_thread_stack(new,old) do { } while(0)
+
+static inline unsigned long *end_of_stack(const struct task_struct *task)
+{
+ return task->stack;
+}
+
+#elif !defined(__HAVE_THREAD_FUNCTIONS)
+
+#define task_stack_page(task) ((void *)(task)->stack)
+
+static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
+{
+ *task_thread_info(p) = *task_thread_info(org);
+ task_thread_info(p)->task = p;
+}
+
+/*
+ * Return the address of the last usable long on the stack.
+ *
+ * When the stack grows down, this is just above the thread
+ * info struct. Going any lower will corrupt the threadinfo.
+ *
+ * When the stack grows up, this is the highest address.
+ * Beyond that position, we corrupt data on the next page.
+ */
+static inline unsigned long *end_of_stack(struct task_struct *p)
+{
+#ifdef CONFIG_STACK_GROWSUP
+ return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
+#else
+ return (unsigned long *)(task_thread_info(p) + 1);
+#endif
+}
+
+#endif
+
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+ return atomic_inc_not_zero(&tsk->stack_refcount) ?
+ task_stack_page(tsk) : NULL;
+}
+
+extern void put_task_stack(struct task_struct *tsk);
+#else
+static inline void *try_get_task_stack(struct task_struct *tsk)
+{
+ return task_stack_page(tsk);
+}
+
+static inline void put_task_stack(struct task_struct *tsk) {}
+#endif
+
+#define task_stack_end_corrupted(task) \
+ (*(end_of_stack(task)) != STACK_END_MAGIC)
+
+static inline int object_is_on_stack(void *obj)
+{
+ void *stack = task_stack_page(current);
+
+ return (obj >= stack) && (obj < (stack + THREAD_SIZE));
+}
+
+extern void thread_stack_cache_init(void);
+
+#ifdef CONFIG_DEBUG_STACK_USAGE
+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
+}
+#endif
+extern void set_task_stack_end_magic(struct task_struct *tsk);
+
#endif /* _LINUX_SCHED_TASK_STACK_H */
--
2.7.4