thread_info: move function declarations to linux/thread_info.h

There are a few __weak functions in kernel/fork.c, which architectures
can override. If there is no prototype, the compiler warns about them:

kernel/fork.c:164:13: error: no previous prototype for 'arch_release_task_struct' [-Werror=missing-prototypes]
kernel/fork.c:991:20: error: no previous prototype for 'arch_task_cache_init' [-Werror=missing-prototypes]
kernel/fork.c:1086:12: error: no previous prototype for 'arch_dup_task_struct' [-Werror=missing-prototypes]

There are already prototypes in a number of architecture specific headers
that have addressed those warnings before, but it's much better to have
these in a single place so the warning no longer shows up anywhere.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnd Bergmann <[e-mail]>
Cc: Boqun Feng <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: Dennis Zhou <[e-mail]>
Cc: Eric Paris <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Michal Simek <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Paul Moore <[e-mail]>
Cc: Pavel Machek <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rafael J. Wysocki <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Tejun Heo <[e-mail]>
Cc: Thomas Bogendoerfer <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Waiman Long <[e-mail]>
Cc: Will Deacon <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

arch/arm64/include/asm/thread_info.h

···
 void arch_setup_new_exec(void);
 #define arch_setup_new_exec     arch_setup_new_exec
 
-void arch_release_task_struct(struct task_struct *tsk);
-int arch_dup_task_struct(struct task_struct *dst,
-				struct task_struct *src);
-
 #endif
 
 #define TIF_SIGPENDING		0	/* signal pending */

arch/s390/include/asm/thread_info.h

···
 
 struct task_struct;
 
-void arch_release_task_struct(struct task_struct *tsk);
-int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
-
 void arch_setup_new_exec(void);
 #define arch_setup_new_exec arch_setup_new_exec
 

arch/sh/include/asm/thread_info.h

···
 
 #define THREAD_SIZE_ORDER	(THREAD_SHIFT - PAGE_SHIFT)
 
-extern void arch_task_cache_init(void);
-extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
-extern void arch_release_task_struct(struct task_struct *tsk);
 extern void init_thread_xstate(void);
 
 #endif /* __ASSEMBLY__ */

arch/x86/include/asm/thread_info.h

···
 			   current_thread_info()->status & TS_COMPAT)
 #endif
 
-extern void arch_task_cache_init(void);
-extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
-extern void arch_release_task_struct(struct task_struct *tsk);
 extern void arch_setup_new_exec(void);
 #define arch_setup_new_exec arch_setup_new_exec
 #endif	/* !__ASSEMBLY__ */

include/linux/thread_info.h

···
 static inline void arch_setup_new_exec(void) { }
 #endif
 
+void arch_task_cache_init(void); /* for CONFIG_SH */
+void arch_release_task_struct(struct task_struct *tsk);
+int arch_dup_task_struct(struct task_struct *dst,
+				struct task_struct *src);
+
 #endif	/* __KERNEL__ */
 
 #endif /* _LINUX_THREAD_INFO_H */