static void sysvipc_proc_stop(struct seq_file *s, void *it)
{
	struct kern_ipc_perm *ipc = it;
	struct ipc_proc_iter *iter = s->private;
	struct ipc_proc_iface *iface = iter->iface;
	struct ipc_ids *ids;

	/* If we had a locked structure, release it */
	if (ipc && ipc != SEQ_START_TOKEN)
		ipc_unlock(ipc);

	ids = &iter->ns->ids[iface->ids];
	/* Release the lock we took in start() */
	up_read(&ids->rwsem);
}

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.