static void mac80211_hwsim_monitor_ack(struct ieee80211_channel *chan,
				       const u8 *addr)
{
	struct sk_buff *skb;
	struct hwsim_radiotap_ack_hdr *hdr;
	u16 flags;
	struct ieee80211_hdr *hdr11;

	if (!netif_running(hwsim_mon))
		return;

	skb = dev_alloc_skb(100);
	if (skb == NULL)
		return;

	hdr = skb_put(skb, sizeof(*hdr));
	hdr->hdr.it_version = PKTHDR_RADIOTAP_VERSION;
	hdr->hdr.it_pad = 0;
	hdr->hdr.it_len = cpu_to_le16(sizeof(*hdr));
	hdr->hdr.it_present = cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
					  (1 << IEEE80211_RADIOTAP_CHANNEL));
	hdr->rt_flags = 0;
	hdr->pad = 0;
	hdr->rt_channel = cpu_to_le16(chan->center_freq);
	flags = IEEE80211_CHAN_2GHZ;
	hdr->rt_chbitmask = cpu_to_le16(flags);

	hdr11 = skb_put(skb, 10);
	hdr11->frame_control = cpu_to_le16(IEEE80211_FTYPE_CTL |
					   IEEE80211_STYPE_ACK);
	hdr11->duration_id = cpu_to_le16(0);
	memcpy(hdr11->addr1, addr, ETH_ALEN);

	skb->dev = hwsim_mon;
	skb_reset_mac_header(skb);
	skb->ip_summed = CHECKSUM_UNNECESSARY;
	skb->pkt_type = PACKET_OTHERHOST;
	skb->protocol = htons(ETH_P_802_2);
	memset(skb->cb, 0, sizeof(skb->cb));
	netif_rx(skb);
}

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.