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Full Discussion: semaphore removal
Top Forums UNIX for Dummies Questions & Answers semaphore removal Post 302471606 by jim mcnamara on Sunday 14th of November 2010 05:29:07 AM
Old 11-14-2010
What you are asking is not clear. The only time 600 helps is when the other processes are from another user in another group. And then they cannot do anything with the sempahore anyway, so it becomes pointless for most applications.

IMO, the real issue is: the only process that should ever be able to execute sem_init() or sem_destroy() must be the same one. The other processes should not have access to that code segment. i.e., after fork(), the child process code path does not have sem_destroy() in it. Any other plan means that one of the child processes could clobber the semaphore, the result being undefined.
 

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SEM_DESTROY(3)						     Linux Programmer's Manual						    SEM_DESTROY(3)

NAME
sem_destroy - destroy an unnamed semaphore SYNOPSIS
#include <semaphore.h> int sem_destroy(sem_t *sem); Link with -pthread. DESCRIPTION
sem_destroy() destroys the unnamed semaphore at the address pointed to by sem. Only a semaphore that has been initialized by sem_init(3) should be destroyed using sem_destroy(). Destroying a semaphore that other processes or threads are currently blocked on (in sem_wait(3)) produces undefined behavior. Using a semaphore that has been destroyed produces undefined results, until the semaphore has been reinitialized using sem_init(3). RETURN VALUE
sem_destroy() returns 0 on success; on error, -1 is returned, and errno is set to indicate the error. ERRORS
EINVAL sem is not a valid semaphore. ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +--------------+---------------+---------+ |Interface | Attribute | Value | +--------------+---------------+---------+ |sem_destroy() | Thread safety | MT-Safe | +--------------+---------------+---------+ CONFORMING TO
POSIX.1-2001, POSIX.1-2008. NOTES
An unnamed semaphore should be destroyed with sem_destroy() before the memory in which it is located is deallocated. Failure to do this can result in resource leaks on some implementations. SEE ALSO
sem_init(3), sem_post(3), sem_wait(3), sem_overview(7) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2017-09-15 SEM_DESTROY(3)
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