NAME
__clear_user - Zero a block of memory in user space, with less
checking.
SYNOPSIS
unsigned long __clear_user (void __user * to, unsigned long n);
ARGUMENTS
to Destination address, in user space.
n Number of bytes to zero.
DESCRIPTION
Zero a block of memory in user space. Caller must check the specified
block with access_ok before calling this function.
Returns number of bytes that could not be cleared. On success, this
will be zero.