suse man page for task_current_syscall

TASK_CURRENT_SYSCALL(9) 					   Machine State					   TASK_CURRENT_SYSCALL(9)

NAME
       task_current_syscall - Discover what a blocked task is doing.

SYNOPSIS
       int task_current_syscall(struct task_struct * target, long * callno, unsigned long args[6], unsigned int maxargs, unsigned long * sp,
				unsigned long * pc);

ARGUMENTS
       target
	   thread to examine

       callno
	   filled with system call number or -1

       args[6]
	   filled with maxargs system call arguments

       maxargs
	   number of elements in args to fill

       sp
	   filled with user stack pointer

       pc
	   filled with user PC

DESCRIPTION
       If target is blocked in a system call, returns zero with *callno set to the the call's number and args filled in with its arguments.
       Registers not used for system call arguments may not be available and it is not kosher to use struct user_regset calls while the system
       call is still in progress. Note we may get this result if target has finished its system call but not yet returned to user mode, such as
       when it's stopped for signal handling or syscall exit tracing.

       If target is blocked in the kernel during a fault or exception, returns zero with *callno set to -1 and does not fill in args. If so, it's
       now safe to examine target using struct user_regset get calls as long as we're sure target won't return to user mode.

       Returns -EAGAIN if target does not remain blocked.

       Returns -EINVAL if maxargs is too large (maximum is six).

Kernel Hackers Manual 2.6.					     July 2010						   TASK_CURRENT_SYSCALL(9)