Re: SHM and programs unable to attach to shm segments

From: Christoph Rohland (
Date: Thu Mar 16 2000 - 11:57:52 EST

Bruno Haible <> writes:

> I'd be glad if you were moving towards shm_open/shm_unlink, because that
> has the right auto-cleanup functionality and therefore has low
> administration overhead:
> The shm_unlink() function removes the name of the shared memory
> object named by the string pointed to by name. If one or more
> references to the shared memory object exist when the object is
> unlinked, the name is removed before shm_unlink() returns, but
> the removal of the memory object contents is postponed until
> all open and map references to the shared memory object have
> been removed.
> But until that is implemented in kernel+glibc, we need the previous
> auto-cleanup feature.

And that's exactly what I implemented in the Linux kernel. I will
make the glibc proposal as soon as the kernel issues have settled

And for the SYSV IPC case: Can you remove the segment after the last
attach? Or is this a segment which should be connectable as long as
the server is up? In the latter case you will need fd passing for
shm_open/shm_unlink to hand the open fd to the other process.


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