suse man page for user_regset_writeback_fn

USER_REGSET_WRITEBAC(9) 					   Machine State					   USER_REGSET_WRITEBAC(9)

NAME
       user_regset_writeback_fn - type of writeback function in struct user_regset

SYNOPSIS
       typedef int user_regset_writeback_fn(struct task_struct * target, const struct user_regset * regset, int immediate);

ARGUMENTS
       target
	   thread being examined

       regset
	   regset being examined

       immediate
	   zero if writeback at completion of next context switch is OK

DESCRIPTION
       This call is optional; usually the pointer is NULL. When provided, there is some user memory associated with this regset's hardware, such
       as memory backing cached register data on register window machines; the regset's data controls what user memory is used (e.g. via the stack
       pointer value).

       Write register data back to user memory. If the immediate flag is nonzero, it must be written to the user memory so uaccess or
       access_process_vm can see it when this call returns; if zero, then it must be written back by the time the task completes a context switch
       (as synchronized with wait_task_inactive). Return 0 on success or if there was nothing to do, -EFAULT for a memory problem (bad stack
       pointer or whatever), or -EIO for a hardware problem.

Kernel Hackers Manual 2.6.					     July 2010						   USER_REGSET_WRITEBAC(9)