fork: move the real prepare_to_copy() users to arch_dup_task_struct()

Historical prepare_to_copy() is mostly a no-op, duplicated for majority of
the architectures and the rest following the x86 model of flushing the extended
register state like fpu there.

Remove it and use the arch_dup_task_struct() instead.

Suggested-by: Oleg Nesterov <[e-mail]>
Suggested-by: Linus Torvalds <[e-mail]>
Signed-off-by: Suresh Siddha <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Acked-by: Benjamin Herrenschmidt <[e-mail]>
Cc: David Howells <[e-mail]>
Cc: Koichi Yasutake <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Paul Mundt <[e-mail]>
Cc: Chris Zankel <[e-mail]>
Cc: Richard Henderson <[e-mail]>
Cc: Russell King <[e-mail]>
Cc: Haavard Skinnemoen <[e-mail]>
Cc: Mike Frysinger <[e-mail]>
Cc: Mark Salter <[e-mail]>
Cc: Aurelien Jacquiot <[e-mail]>
Cc: Mikael Starvik <[e-mail]>
Cc: Yoshinori Sato <[e-mail]>
Cc: Richard Kuo <[e-mail]>
Cc: Tony Luck <[e-mail]>
Cc: Michal Simek <[e-mail]>
Cc: Ralf Baechle <[e-mail]>
Cc: Jonas Bonn <[e-mail]>
Cc: James E.J. Bottomley <[e-mail]>
Cc: Helge Deller <[e-mail]>
Cc: Martin Schwidefsky <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Chen Liqin <[e-mail]>
Cc: Lennox Wu <[e-mail]>
Cc: David S. Miller <[e-mail]>
Cc: Chris Metcalf <[e-mail]>
Cc: Jeff Dike <[e-mail]>
Cc: Richard Weinberger <[e-mail]>
Cc: Guan Xuetao <[e-mail]>
Signed-off-by: H. Peter Anvin <[e-mail]>

arch/alpha/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /* Create a kernel thread without removing it from tasklists.  */
 extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 

arch/arm/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 unsigned long get_wchan(struct task_struct *p);
 
 #if __LINUX_ARM_ARCH__ == 6 || defined(CONFIG_ARM_ERRATA_754327)

arch/avr32/include/asm/processor.h

···
 /* Create a kernel thread without removing it from tasklists */
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk) do { } while(0)
-
 /* Return saved PC of a blocked thread */
 #define thread_saved_pc(tsk)    ((tsk)->thread.cpu_context.pc)
 

arch/blackfin/include/asm/processor.h

···
 {
 }
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags);
 
 /*

arch/c6x/include/asm/processor.h

···
 {
 }
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 #define copy_segments(tsk, mm)		do { } while (0)

arch/cris/include/asm/processor.h

···
 #define task_pt_regs(task) user_regs(task_thread_info(task))
 #define current_regs() task_pt_regs(current)
 
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 unsigned long get_wchan(struct task_struct *p);

arch/frv/include/asm/processor.h

···
 	__frame->sp	= (_usp);			\
 } while(0)
 
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /* Free all resources held by a thread. */
 static inline void release_thread(struct task_struct *dead_task)
 {

arch/frv/kernel/process.c

···
 	return do_fork(clone_flags, newsp, __frame, 0, parent_tidptr, child_tidptr);
 } /* end sys_clone() */
 
-/*****************************************************************************/
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	//unlazy_fpu(tsk);
-} /* end prepare_to_copy() */
-
-/*****************************************************************************/
 /*
  * set up the kernel stack and exception frames for a new process
  */

arch/h8300/include/asm/processor.h

···
 
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * Free current thread data structures etc..
  */

arch/hexagon/include/asm/processor.h

···
 #define cpu_relax() __vmyield()
 
 /*
- * "Unlazying all lazy status" occurs here.
- */
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
-/*
  * Decides where the kernel will search for a free chunk of vm space during
  * mmaps.
  * See also arch_get_unmapped_area.

arch/ia64/include/asm/processor.h

···
  */
 #define release_thread(dead_task)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * This is the mechanism for creating a new kernel thread.
  *

arch/m32r/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * create a kernel thread without removing it from tasklists
  */

arch/m68k/include/asm/processor.h

···
 {
 }
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 /*

arch/microblaze/include/asm/processor.h

···
 
 # define cpu_relax()		barrier()
 # define cpu_sleep()		do {} while (0)
-# define prepare_to_copy(tsk)	do {} while (0)
 
 #define task_pt_regs(tsk) \
 		(((struct pt_regs *)(THREAD_SIZE + task_stack_page(tsk))) - 1)

arch/mips/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 #define release_thread(thread) do { } while(0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern long kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long thread_saved_pc(struct task_struct *tsk);

arch/mn10300/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /*
  * create a kernel thread without removing it from tasklists
  */

arch/mn10300/kernel/process.c

···
 }
 
 /*
- * this gets called before we allocate a new thread and copy the current task
- * into it so that we can store lazy state into memory
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
-	unlazy_fpu(tsk);
+	unlazy_fpu(src);
+	*dst = *src;
+	return 0;
 }
 
 /*

arch/openrisc/include/asm/processor.h

···
 #define task_pt_regs(task) user_regs(task_thread_info(task))
 #define current_regs() user_regs(current_thread_info())
 
-extern inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
 #define INIT_SP         (sizeof(init_stack) + (unsigned long) &init_stack)
 
 #define INIT_THREAD  { }

arch/parisc/include/asm/processor.h

···
 extern void release_thread(struct task_struct *);
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern void map_hpux_gateway_page(struct task_struct *tsk, struct mm_struct *mm);
 
 extern unsigned long get_wchan(struct task_struct *p);

arch/powerpc/include/asm/processor.h

···
 void start_thread(struct pt_regs *regs, unsigned long fdptr, unsigned long sp);
 void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 /* Create a new kernel thread. */
 extern long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 

arch/powerpc/kernel/process.c

···
 }
 
 /*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
+ * this gets called so that we can store coprocessor state into memory and
+ * copy the current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
-	flush_fp_to_thread(current);
-	flush_altivec_to_thread(current);
-	flush_vsx_to_thread(current);
-	flush_spe_to_thread(current);
+	flush_fp_to_thread(src);
+	flush_altivec_to_thread(src);
+	flush_vsx_to_thread(src);
+	flush_spe_to_thread(src);
 #ifdef CONFIG_HAVE_HW_BREAKPOINT
-	flush_ptrace_hw_breakpoint(tsk);
+	flush_ptrace_hw_breakpoint(src);
 #endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+	*dst = *src;
+	return 0;
 }
 
 /*

arch/s390/include/asm/processor.h

···
 extern void release_thread(struct task_struct *);
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 /*
  * Return saved PC of a blocked thread.
  */

arch/score/include/asm/processor.h

···
 
 #define cpu_relax()		barrier()
 #define release_thread(thread)	do {} while (0)
-#define prepare_to_copy(tsk)	do {} while (0)
 
 /*
  * User space process size: 2GB. This is hardcoded into a few places,

arch/sh/include/asm/processor_32.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-void prepare_to_copy(struct task_struct *tsk);
-
 /*
  * create a kernel thread without removing it from tasklists
  */

arch/sh/include/asm/processor_64.h

···
 #define copy_segments(p, mm)	do { } while (0)
 #define release_segments(mm)	do { } while (0)
 #define forget_segments()	do { } while (0)
-#define prepare_to_copy(tsk)	do { } while (0)
 /*
  * FPU lazy state save handling.
  */

arch/sh/kernel/process.c

···
 struct kmem_cache *task_xstate_cachep = NULL;
 unsigned int xstate_size;
 
+/*
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
+ */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
+#ifdef CONFIG_SUPERH32
+	unlazy_fpu(src, task_pt_regs(src));
+#endif
 	*dst = *src;
 
 	if (src->thread.xstate) {

arch/sh/kernel/process_32.c

···
 }
 EXPORT_SYMBOL(dump_fpu);
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk, task_pt_regs(tsk));
-}
-
 asmlinkage void ret_from_fork(void);
 
 int copy_thread(unsigned long clone_flags, unsigned long usp,

arch/sparc/include/asm/processor_32.h

···
 #define release_thread(tsk)		do { } while(0)
 extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern unsigned long get_wchan(struct task_struct *);
 
 #define task_pt_regs(tsk) ((tsk)->thread.kregs)

arch/sparc/include/asm/processor_64.h

···
 /* Free all resources held by a thread. */
 #define release_thread(tsk)		do { } while (0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern pid_t kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
 extern unsigned long get_wchan(struct task_struct *task);

arch/tile/include/asm/processor.h

···
 	/* Nothing for now */
 }
 
-/* Prepare to copy thread state - unlazy all lazy status. */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
 
 extern int do_work_pending(struct pt_regs *regs, u32 flags);

arch/um/include/asm/processor-generic.h

···
 
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 
-static inline void prepare_to_copy(struct task_struct *tsk)
-{
-}
-
-
 extern unsigned long thread_saved_pc(struct task_struct *t);
 
 static inline void mm_copy_segments(struct mm_struct *from_mm,

arch/unicore32/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy status */
-#define prepare_to_copy(tsk)	do { } while (0)
-
 unsigned long get_wchan(struct task_struct *p);
 
 #define cpu_relax()			barrier()

arch/x86/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 extern void release_thread(struct task_struct *);
 
-/* Prepare to copy thread state - unlazy all lazy state */
-extern void prepare_to_copy(struct task_struct *tsk);
-
 unsigned long get_wchan(struct task_struct *p);
 
 /*

arch/x86/kernel/process.c

···
 struct kmem_cache *task_xstate_cachep;
 EXPORT_SYMBOL_GPL(task_xstate_cachep);
 
+/*
+ * this gets called so that we can store lazy state into memory and copy the
+ * current task into the new thread.
+ */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 	int ret;
+
+	unlazy_fpu(src);
 
 	*dst = *src;
 	if (fpu_allocated(&src->thread.fpu)) {

arch/x86/kernel/process_32.c

···
 	release_vm86_irqs(dead_task);
 }
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk);
-}
-
 int copy_thread(unsigned long clone_flags, unsigned long sp,
 	unsigned long unused,
 	struct task_struct *p, struct pt_regs *regs)

arch/x86/kernel/process_64.c

···
 	return get_desc_base(&t->thread.tls_array[tls]);
 }
 
-/*
- * This gets called before we allocate a new thread and copy
- * the current task into it.
- */
-void prepare_to_copy(struct task_struct *tsk)
-{
-	unlazy_fpu(tsk);
-}
-
 int copy_thread(unsigned long clone_flags, unsigned long sp,
 		unsigned long unused,
 	struct task_struct *p, struct pt_regs *regs)

arch/xtensa/include/asm/processor.h

···
 /* Free all resources held by a thread. */
 #define release_thread(thread) do { } while(0)
 
-/* Prepare to copy thread state - unlazy all lazy status */
-extern void prepare_to_copy(struct task_struct*);
-
 /* Create a kernel thread without removing it from tasklists */
 extern int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags);
 

arch/xtensa/kernel/process.c

···
 }
 
 /*
- * This is called before the thread is copied. 
+ * this gets called so that we can store coprocessor state into memory and
+ * copy the current task into the new thread.
  */
-void prepare_to_copy(struct task_struct *tsk)
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 #if XTENSA_HAVE_COPROCESSORS
-	coprocessor_flush_all(task_thread_info(tsk));
+	coprocessor_flush_all(task_thread_info(src));
 #endif
+	*dst = *src;
+	return 0;
 }
 
 /*

kernel/fork.c

···
 	int node = tsk_fork_get_node(orig);
 	int err;
 
-	prepare_to_copy(orig);
-
 	tsk = alloc_task_struct_node(node);
 	if (!tsk)
 		return NULL;