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From: ndunstan@gara.une.oz.au (Neil Dunstan)
Newsgroups: comp.unix.internals
Subject: Trouble using semctl
Message-ID: <5456@gara.une.oz.au>
Date: 25 Feb 91 23:27:23 GMT
Reply-To: ndunstan@gara.une.oz.au (Neil Dunstan)
Organization: Uni. of New England, Armidale, NSW.
Lines: 35

semctl( semarray_id, 0, GETNCNT, 0 ) sometimes returns 0 unexpectedly.

I'm using it in a loop to test when a process has been released from a semaphore
queue. i.e.

oldcount = semctl( semarray_id, 0, GETNCNT, 0 )
while( (newcount = semctl( semarray_id, 0, GETCNT, 0 )) != oldcount-1 )
	semop( ... /* increase semaphore value by one */

Does anyone know why this shouldn't work?

Thanks.
Newsgroups: comp.unix.internals
Subject: Problem with semctl
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Reply-To: neil@neumann.une.oz (Neil Dunstan)
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Organization: University of New England, Armidale, Australia
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semctl( semarray_id, 0, GETNCNT, 0 ) sometimes returns 0 unexpectedly.

I'm using it in a loop to test when a process has been released from a semaphore
queue. i.e.

oldcount = semctl( semarray_id, 0, GETNCNT, 0 )
while( (newcount = semctl( semarray_id, 0, GETCNT, 0 )) != oldcount-1 )
	semop( ... /* increase semaphore value by one */

Does anyone know why this shouldn't work?

Thanks.


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