Re: [Xen-devel] [PATCH v2] libxl: prepare environment for domcreate_stream_done

[Ian Jackson <ian.jackson@xxxxxxxxxx>]

Olaf Hering writes ("[PATCH v2] libxl: prepare environment for 
domcreate_stream_done"):
> The function domcreate_bootloader_done may branch early to
> domcreate_stream_done, in case some error occoured. Here srs->dcs will be
> NULL, which leads to a crash.

Thanks.  I think this is OK as far as it goes.  But:

> +    /* Prepare environment for domcreate_stream_done */
> +    dcs->srs.dcs = dcs;

The need for this comment is telling us something about the weird code
structure here.  We initialise all of dcs->srs much later, so even
with this change we call domcreate_stream_done with a
mostly-uninitialised srs.

In fact this is OK because domcreate_stream_done only reads srs->dcs
and then does everything with the obtained dcs.  But there is nothing
there to indicate that srs might be mostly uninitialised.  Maybe we
could add a comment there, something like:

  /* NB perhaps only srs->dcs is valid; eg in the case of an
   * early branch to domcreate_bootloader_done's `out' block */

?

Ian.

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