Re: [Xen-devel] [PATCH] xenstore: set READ_THREAD_STACKSIZE to a sane value

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-03-12 at 11:27 +0100, Roger Pau Monnà wrote:
> On 11/03/14 17:52, Ian Jackson wrote:
> > Roger Pau Monnà writes ("Re: [PATCH] xenstore: set READ_THREAD_STACKSIZE to 
> > a sane value"):
> >> On 11/03/14 17:25, Ian Jackson wrote:
> >>> Well, actually, a malloc works, doesn't it ?
> >>
> >> No, actually a malloc with PTHREAD_STACK_MIN doesn't work, this sample 
> >> example program fails in the same way:
> > 
> > Wow.  I'm sure that can't be intentional.
> 
> According to
> http://pubs.opengroup.org/onlinepubs/7908799/xsh/limits.h.html (or at
> least that's how I read it), it shouldn't be assumed that
> PTHREAD_STACK_MIN will be set to a value that allows using libc calls,
> the standard even says it's valid to set it to 0.

That's not a terribly helpful definition!

I don't remember seeing that when I wrote that older version.
http://pubs.opengroup.org/onlinepubs/009695399/functions/pthread_attr_setstacksize.html
 doesn't feel the need to talk about such things, which is rather unhelpful of 
it...

> So I think the proposed patch (or a variation of it), is the right
> solution, we shouldn't rely on PTHREAD_STACK_MIN being set to a sane
> value. IMHO the only thing we should use PTHREAD_STACK_MIN for is to
> check that the value we are passing to pthread_attr_setstacksize is valid.

Yeah, it does seem that way.

Ian.


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