Two processes P$1$ and P$2$ are concurrently attempting to access a single resource in a mutually exclusive manner using the semaphore operation wait$().$ It is claimed the wait$()$ and signal$()$ operations on semaphores must be implemented atomically or in an indivisible fashion. What if this wait$()$ is implemented as an ordinary function $($or procedure$)$ without being atomic?

The wait$()$ semaphore operation can be defined as

wait$($semaphore $*$S$)\{$

S$->$value$--$;

if $($S$->$value $<0)\{$

add this process to S$->$list;

block$()$;

$\}$

$\}$