Description:
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Two processes - processA and processB - are using a semaphore.

processA sem_get()s the semaphore. (the semaphore is created)
processB sem_get()s the semaphore. (the semaphore is already created, so the semaphore id is just returned)

processA sem_acquire()s the semaphore and begins to work in the critical section.
processB sem_acquire()s the semaphore and BLOCKS.

processA finishes in it's critical section and sem_release()s.
processA sem_remove()s the semaphore ***THE SEMAPHORE HAS NOW BEEN REMOVED - 
I think that this part is incorrect****

processB now is NOT able to continue as the semaphore has been removed.


sem_remove() should take the SYSVSEM_USAGE (see sysvsem.c) count into consideration when it is called. Only if this count is == 1 should the semaphore be removed. This will allow the last process that is using the semaphore to remove it from the system.




Reproduce code:
---------------
<?php
//Note - run this script from two different clients at the same time.
//add your own critical section code and output logging.
$semKey = 1234;
$semHandle = sem_get($semKey, 1, 0666, FALSE);

sem_acquire($semHandle);
//critical section
//do something useful here
sem_release($semHandle);


sem_remove($semHandle);

?>



Expected result:
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processA and processB both able to work in their critical sections without error.

Actual result:
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Log messages such as the following are generated:

[13-Feb-2008 14:36:30] PHP Warning:  sem_acquire() [<a href='function.sem-acquire'>function.sem-acquire</a>]: failed to acquire key 0x2b72: Invalid argument in /opt/MarkDW/Exec/Form.php on line 1282