Function dpcpu_alloc

freebsd/kern/subr_pcpu.c:164–190

* First-fit extent based allocator for allocating space in the per-cpu * region reserved for modules. This is only intended for use by the * kernel linkers to place module linker sets. */

 * kernel linkers to place module linker sets.
 */
void *
dpcpu_alloc(int size)
{
	struct dpcpu_free *df;
	void *s;

	s = NULL;
	size = roundup2(size, sizeof(void *));
	sx_xlock(&dpcpu_lock);
	TAILQ_FOREACH(df, &dpcpu_head, df_link) {
		if (df->df_len < size)
			continue;
		if (df->df_len == size) {
			s = (void *)df->df_start;
			TAILQ_REMOVE(&dpcpu_head, df, df_link);
			free(df, M_PCPU);
			break;
		}
		s = (void *)df->df_start;
		df->df_len -= size;
		df->df_start = df->df_start + size;
		break;
	}
	sx_xunlock(&dpcpu_lock);

	return (s);
}

/*
 * Free dynamic per-cpu space at module unload time.