Re: [Xen-devel] [PATCH v2 16/27] tools/libxl: Infrastructure for reading a libxl migration v2 stream

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Andrew Cooper writes ("Re: [PATCH v2 16/27] tools/libxl: Infrastructure for 
reading a libxl migration v2 stream"):
> On 10/07/15 12:25, Ian Campbell wrote:
> > Do you mean they would do so legitimately in that case, or in error?
> 
> It is wrong in all cases to mutually recurse like this.  The data
> controlling the degree of mutual recursion is read from a pipe.
> 
> The issue with the TOOLSTACK record is that it a synchronous library
> call, not an aync one.  This is not a problem pe say, but it means that
> process_record() must queue something further to do.
> 
> In a checkpoint it is possible (although very unlikely) to have $N
> thousand TOOLSTACK records back to back.
> 
> The guards are in place to prevent introducing a codepath which does end
> up in mutual recursion.  Such a calltree would function for any
> reasonable input, but would fall off the stack given a certain sequence
> of records.

I just wanted to say that I have read this and it helps my
understanding but I still worry about the correctness of
stream_continue and process_record if the queue has more than one
record.

Ian.

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