Function vmem_xalloc

freebsd/kern/subr_vmem.c:1354–1460

}

int
vmem_xalloc(vmem_t *vm, const vmem_size_t size0, vmem_size_t align,
    const vmem_size_t phase, const vmem_size_t nocross,
    const vmem_addr_t minaddr, const vmem_addr_t maxaddr, int flags,
    vmem_addr_t *addrp)
{
	const vmem_size_t size = vmem_roundup_size(vm, size0);
	struct vmem_freelist *list;
	struct vmem_freelist *first;
	struct vmem_freelist *end;
	bt_t *bt;
	int error;
	int strat;

	flags &= VMEM_FLAGS;
	strat = flags & VMEM_FITMASK;
	MPASS(size0 > 0);
	MPASS(size > 0);
	MPASS(strat == M_BESTFIT || strat == M_FIRSTFIT || strat == M_NEXTFIT);
	MPASS((flags & (M_NOWAIT|M_WAITOK)) != (M_NOWAIT|M_WAITOK));
	if ((flags & M_NOWAIT) == 0)
		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "vmem_xalloc");
	MPASS((align & vm->vm_quantum_mask) == 0);
	MPASS((align & (align - 1)) == 0);
	MPASS((phase & vm->vm_quantum_mask) == 0);
	MPASS((nocross & vm->vm_quantum_mask) == 0);
	MPASS((nocross & (nocross - 1)) == 0);
	MPASS((align == 0 && phase == 0) || phase < align);
	MPASS(nocross == 0 || nocross >= size);
	MPASS(minaddr <= maxaddr);
	MPASS(!VMEM_CROSS_P(phase, phase + size - 1, nocross));
	if (strat == M_NEXTFIT)
		MPASS(minaddr == VMEM_ADDR_MIN && maxaddr == VMEM_ADDR_MAX);

	if (align == 0)
		align = vm->vm_quantum_mask + 1;
	*addrp = 0;

	/*
	 * Next-fit allocations don't use the freelists.
	 */
	if (strat == M_NEXTFIT)
		return (vmem_xalloc_nextfit(vm, size0, align, phase, nocross,
		    flags, addrp));

	end = &vm->vm_freelist[VMEM_MAXORDER];
	/*
	 * choose a free block from which we allocate.
	 */
	first = bt_freehead_toalloc(vm, size, strat);
	VMEM_LOCK(vm);

	/*
	 * Make sure we have enough tags to complete the operation.
	 */
	error = bt_fill(vm, flags);
	if (error != 0)
		goto out;