Re: [Qemu-devel] [PATCH 04/18] savevm: set right return value for qemu_file_rate_limit

[Paolo Bonzini <pbonzini@redhat.com>]

> Say, In ram_save_iterate(), the current logic is:
> 
> ret = qemu_file_rate_limit();
> while(ret == 0) {
>      save RAM blocks until no more to send.
> }
> if (ret < 0) {
>      return ret;
> }
> ...
> 
> And in savevm layer, qemu_savevm_state_iterate() set an error if the return
> value of ram_save_iterate < 0.

But that is to report errors *not in the QEMUFile*.  Errors in the
QEMUFile are already reported by qemu_file_get_error(), and
qemu_savevm_state_iterate() will not overwrite them.

qemu_file_rate_limit() returning 1 is enough to exit the loop,
which is all that is needed.

> Obviously the return value of qemu_file_rate_limit() should have an negative
> value for there has been an error. Otherwise we need to modify the logic
> above.

It is not obvious to me... what is, again, the bug that you're observing?
I think it is happening only because you're modifying the migration thread's
body.  If you use the normal code of the migration thread, it will just work.

Paolo