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Example for use of kernel semaphore

 
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Old 03-14-2006
Example for use of kernel semaphore
Hi friends I'm doing a project and in that I need to use kernel semaphore but I'm not very clear about how to use it. I've used system V semaphore.
What I find difficult to understand is that in system V semaphore, a semaphore set is registered to the system (the semid returned from semget call is unique and can identify the semaphore set) allowing synchronisation between processes as against this in kernel semaphore it seems to me only a instance of structure semaphore needs to be created and up() and down() called upon it for synchronisation. But how can an instance of structure declared in one program be known in other program.

May be I'm thinking wrong way plz. rectify me if so and plz. show me an example how to use kernel semaphore.
Thanks in advance
Last edited by Rakesh Ranjan; 03-16-2006 at 05:01 AM..
 
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LEARN ABOUT HPUX

sem_destroy

sem_destroy(2)							System Calls Manual						    sem_destroy(2)

NAME

       sem_destroy - destroy an unnamed POSIX semaphore

SYNOPSIS

DESCRIPTION

       is  used  to  destroy  an unnamed semaphore.  A successful call to will invalidate the unnamed semaphore referred to by sem and removes all
       descriptors referencing it.  The semaphore should have been created by a previous call to and there should not be any processes blocked	on
       it.

       To use this function, link in the realtime library by specifying on the compiler or linker command line.

EXAMPLES

       The following call to will destroy an unnamed semaphore referred to by sem and remove all descriptors referencing it.

RETURN VALUE

       If the semaphore was destroyed and the descriptors referencing it were removed, returns 0 to the caller.

       If the semaphore could not be destroyed, the call returns -1 and sets to indicate the error.

ERRORS

       fails and does not perform the requested operation if any of the following conditions are encountered:

	      [EBUSY]	     There are threads currently blocked on the semaphore or there are outstanding locks held on the semaphore.

	      [EINVAL]	     The argument sem is not a valid unnamed semaphore.

SEE ALSO

       sem_init(2), sem_open(2), <semaphore.h>.

STANDARDS CONFORMANCE

																    sem_destroy(2)