Re: Question on win32 semaphore simulation

"Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu> wrote
> As I reviewed the win32/sema.c, there is some code that I am not clear,
can
> anybody explain please?
>

There is another problem related to concurrent operations on win32 sema. Say
two processes are doing semop(+1) concurrently. Look at this code:

/* Don't want the lock anymore */
sem_counts[sops[0].sem_num]++;
ReleaseSemaphore(cur_handle, sops[0].sem_op, NULL);

Except for the problem mentioned in the above thread that the first line
should be: sem_counts[sops[0].sem_num] += sops[0].sem_op, the sem_counts[]
are unprotected by anything, so we might lose an update. Maybe I totally
misunderstand something?

Regards,
Qingqing