A Question About kernel source code

A Question About kernel source code

[Feng Chun]

Hello everyone:
	I have a question about the linux source code.

consider the function:get_vm_area( mm/vmalloc.c )
struct vm_struct * get_vm_area(unsigned long size)
{
 	struct vm_struct **p,
	....
	for (p = &vmlist; (tmp = *p) ; p = &tmp->next) {
        if (size + addr < (unsigned long) tmp->addr)
                break;
        addr = tmp->size + (unsigned long) tmp->addr;
        if (addr > VMALLOC_END-size) {
                kfree(area);
                return NULL;
        }
}
....
}

notice that  here p is defined as a pointer to a pointer, why not 

struct vm_struct *p,
for (p=vmlist; (tmp=p); p=tmp->next) {
..
}

does it mean that the later is not efficient as the former? 

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