Function uma_zalloc_arg

freebsd/vm/uma_core.c:3432–3471

See uma.h */

/* See uma.h */
void *
uma_zalloc_arg(uma_zone_t zone, void *udata, int flags)
{
	uma_cache_bucket_t bucket;
	uma_cache_t cache;

	/* Enable entropy collection for RANDOM_ENABLE_UMA kernel option */
	random_harvest_fast_uma(&zone, sizeof(zone), RANDOM_UMA);

	/* This is the fast path allocation */
	CTR3(KTR_UMA, "uma_zalloc_arg zone %s(%p) flags %d", zone->uz_name,
	    zone, flags);

#ifdef UMA_ZALLOC_DEBUG
	void *item;

	KASSERT((zone->uz_flags & UMA_ZONE_SMR) == 0,
	    ("uma_zalloc_arg: called with SMR zone."));
	if (uma_zalloc_debug(zone, &item, udata, flags) == EJUSTRETURN)
		return (item);
#endif

	/*
	 * If possible, allocate from the per-CPU cache.  There are two
	 * requirements for safe access to the per-CPU cache: (1) the thread
	 * accessing the cache must not be preempted or yield during access,
	 * and (2) the thread must not migrate CPUs without switching which
	 * cache it accesses.  We rely on a critical section to prevent
	 * preemption and migration.  We release the critical section in
	 * order to acquire the zone mutex if we are unable to allocate from
	 * the current cache; when we re-acquire the critical section, we
	 * must detect and handle migration if it has occurred.
	 */
	critical_enter();
	cache = &zone->uz_cpu[curcpu];
	bucket = &cache->uc_allocbucket;
	if (__predict_false(bucket->ucb_cnt == 0))
		return (cache_alloc_retry(zone, cache, udata, flags));
	return (cache_alloc_item(zone, cache, bucket, udata, flags));
}

/*
 * Replenish an alloc bucket and possibly restore an old one.  Called in