Re: [Xen-devel] [PATCH RESEND] libxl: Deprecate synchronous waiting for the device model

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2013-11-12 at 16:58 +0000, Ian Jackson wrote:
> Ian Jackson writes ("Re: [PATCH] libxl: Deprecate synchronous waiting for the 
> device model"):
> > Ian Campbell writes ("Re: [PATCH] libxl: Deprecate synchronous waiting for 
> > the device model"):
> > > On Mon, 2013-10-14 at 17:30 +0100, Ian Jackson wrote:
> > > >  /*
> > > > - * libxl__wait_for_offspring - Wait for child state
> > > > + * libxl__xenstore_child_wait_deprecated - Wait for daemonic child IPC
> > > > [...]
> > > > This function is currently used only by
> > > > + * libxl__wait_for_device_model_deprecated.
> > > 
> > > Could it become a static helper in tools/libxl/libxl_device.c (which is
> > > where libxl__wait_for_device_model_deprecated seems to live) then? Tat
> > > would get it out of the internal API immediately...
> > 
> > At the moment its called in libxl_device.c but defined in
> > libxl_exec.c.  I'm not too keen on moving about something which we
> > intend to get rid of.
> 
> Ping.
> 
> 
> From: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Date: Mon, 14 Oct 2013 17:26:01 +0100
> Subject: [PATCH] libxl: Deprecate synchronous waiting for the device model
> 
> libxl__wait_for_device_model blocks, with the ctx lock held, waiting
> for a response from the device model.  If the dm doesn't respond
> quickly (for example, because it has crashed), this may block the
> whole process.  Explain this in a comment, rename the function to
> libxl__wait_for_device_model_deprecated, and explain what to use
> instead.
> 
> libxl__wait_for_offspring is the core implementation for the above.
> Its name leads people to think it might be generally useful for
> waiting for children, which is far from the case.  It only waits for
> xenstore.  Also it has the problems described above.  Explain this,
> rename it to libxl__xenstore_child_wait_deprecated, and explain what
> to use instead.
> 
> Signed-off-by: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>



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