if(addr == -1) 
if(addr == -1UL) 
static int do_op(unsigned long addr, int len, int is_write,		 int (*op)(unsigned long addr, int len, void *arg), void *arg){	struct page *page;	int n;	addr = maybe_map(addr, is_write);	if(addr == -1)		return(-1);	page = phys_to_page(addr);	addr = (unsigned long) kmap(page) + (addr & ~PAGE_MASK);	n = (*op)(addr, len, arg);	kunmap(page);	return(n);}
4520	/local/tlutelli/issta_data/temp/c/2005_temp/2005/4520/2d58cc9a437f3833d242e9d1617ec9b4044e26f3/uaccess.c/clean/arch/um/kernel/skas/uaccess.c