void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
{
	int lid = ipcid_to_idx(ipcp->id);

	idr_remove(&ids->ipcs_idr, lid);
	ids->in_use--;
	ipcp->deleted = true;
}

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.