Re: [Xen-devel] [PATCH v5 10/15] libxl_exec: Add libxl__spawn_initiate_failure

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, Oct 16, 2018 at 03:02:37PM +0100, Ian Jackson wrote:
> Anthony PERARD writes ("[PATCH v5 10/15] libxl_exec: Add 
> libxl__spawn_initiate_failure"):
> > + * The spawn state must be Attached entry and will be Attached Failed
> > + * on return.
> 
>                               Attached on entry
> 
> And, there is no such public state as `Attached Failed'.  That is a
> private state.  The comment about libxl__spawn_initiate_failure
> putting the spawn into state Attached Failed should be in
> libxl_exec.c, next to that function.
> 
> Writing that the state afterwards is still Attached makes it clear
> that this function may be called multiple times.  How about:
> 
>       The spawn state must be Attached on entry and will remain
>       Attached.  It is possible for a spawn to fail for multiple
>       reasons, for example call(s) to libxl__spawn_initiate_failure
>       and also for some other reason.  In that case the last rc value
>       from any source will take precedence.
> 
> But is that really the semantics we want?  Maybe the first or last
> call to libxl__spawn_initiate_failure should take precedence ?

"The first rc value [...] will take precedence" sound better I think,
instead of the last.

I'll modify libxl__spawn_initiate_failure to only set ss->rc if it it
isn't already.

-- 
Anthony PERARD

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