Re: [Xen-devel] [PATCH] libxc: free thread specific hypercall buffer on xc_interface_close

[Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>]

On Thu, 2010-08-19 at 13:39 +0100, Christoph Egger wrote:
> On Wednesday 18 August 2010 18:26:28 Ian Campbell wrote:
> > On Wed, 2010-08-18 at 17:04 +0100, Christoph Egger wrote:
> > > This patch prevents me from starting a guest until
> > > the outstanding issue - namely why is hcall_buf_prep() never called -
> > > is solved.
> >
> > You wouldn't expect hcall_buf_prep to be called if you opened the xc
> > interface and then closed it without doing a hypercall which required
> > any locked down memory.
> >
> > This updated version of the patch was intended to handle exactly this
> > case
> 
> Yes, it works. The issue was in the debug code itself. After
> removing the trace code I am able to start guests again.
> 
> Thanks for your help.

Thanks for confirming.

> > since it appears that under NetBSD it can cause issues. 
> 
> I am wondering why this issue didn't appear on Linux.
> Does Linux have some kind of auto-initialization?

I think it's just good/bad luck one way or the other if an uninitialised
pthread_key_t looks valid to pthread_getspecific or not. Ultimately
pthread_key_t is likely just an integer so there is always a chance that
an uninitialised pthread_key_t looks like an existing valid key.

Ian.


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