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NULLOP(9)		 BSD Kernel Developer's Manual		     NULLOP(9)

NAME
     nullop — dummy functions

SYNOPSIS
     #include <sys/systm.h>

     int
     nullop(void *v);

     void
     voidop(void);

     int
     enodev(void);

     int
     enxio(void);

     int
     enoioctl(void);

     int
     enosys(void);

     int
     eopnotsupp(void);

DESCRIPTION
     The nullop() function provides a generic “null operation”.	 It always
     returns the value 0.  The voidop() function takes no arguments and does
     nothing.

     The enodev(), enxio(), enoioctl(), enosys(), and eopnotsupp() functions
     always fail, returning ENODEV, ENXIO, ENOTTY, ENOSYS, and EOPNOTSUPP,
     respectively.

EXAMPLES
     The following example demonstrates a case where nullop() may be useful:

	   uint64_t xc;

	   ...

	   xc = xc_broadcast(0, (xcfunc_t)nullop, NULL, NULL);
	   xc_wait(xc);

BSD				 July 25, 2010				   BSD

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