If another processor 1 enters the critical region and writes while processor 0 is reading or writing to it, tearing might occur - processor 0 may have read 1 word (out of 2) and processor 1 writes the 2nd word.
If another processor 1 enters the critical region and writes while processor 0 is reading or writing to it, tearing might occur - processor 0 may have read 1 word (out of 2) and processor 1 writes the 2nd word.