Re: [RFC, PATCH] fix SEM_UNDO with namespaces
From: Pavel Emelyanov
Date: Mon Mar 31 2008 - 03:12:49 EST
Manfred Spraul wrote:
> Hi,
>
> the attached patch should fix the combination of CLONE_NEWIPC with
> shared sysv undo structures (the common case, just
> sys_unshare(CLONE_NEWIPC)):
> lookup_undo() now locates the undo array based on both semid and the
> namespace pointer.
If you start using any IPC object and then call unshare with CLONE_NEWIPC,
then it's your problem, but not the kernel. There are many issues that can
become broken from the user-level POV.
What's the problem with undo list? Does it become irrelevant and no undos
happen after the task dies?
I agree, that we should probably destroy this one when the task calls
unshare, but trying to keep this list relevant is useless.
> Additionally, the patch tries to clean the code up by using the linked
> list macros from <linux/list.h> instead of single linked lists.
May I ask you to split the patch into atomic parts, rather than
mixing fixes, reworks and cleanups together?
> The patch passes a few quick tests, I'm interested in feedback. Are
> there test apps for testing the IPC namespace code?
This code is a part of OpenVZ kernels, so it passes some internal
tests we perform.
> --
> Manfred
>
Thanks,
Pavel
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