Re: [Xen-devel] [PATCH] libxl: libxl_internal.h: Clarify ao rule against internal callers

[Juergen Gross <jgross@xxxxxxxx>]

On 06/11/2015 06:57 PM, Ian Jackson wrote:
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Ian Campbell <ian.campbell@xxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> ---
>   tools/libxl/libxl_internal.h |    5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index 465aaaa..bfc0729 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -1911,8 +1911,9 @@ _hidden void libxl__egc_cleanup(libxl__egc *egc);
>    * All "slow" functions (see below for the exact definition) need to
>    * use the asynchronous operation ("ao") machinery.  The function
>    * should take a parameter const libxl_asyncop_how *ao_how and must
> - * start with a call to AO_INITIATOR_ENTRY.  These functions MAY NOT
> - * be called from inside libxl, because they can cause reentrancy
> + * start with a call to AO_CREATE or equivalent.  These functions MAY
> + * NOT be called from inside libxl (regardless of what is passed for
> + * ao_how), because they can cause reentrancy hazards due to
>    * callbacks.
>    *
>    * For the same reason functions taking an ao_how may make themselves
Now it's 100% clear what to avoid.

Acked-by: Juergen Gross <jgross@xxxxxxxx>

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