The new funky way to do all this is with a linked smart object. So the smart object is actually linked to another file - the raw file. Now, if the raw file is in Lightroom, you can use Lr to make further adjustments to it. Save the xmp metadata back to the file, and then in PS you can update the linked smart object. I like this method (at least in theory), and it's easier to do than to describe, but I never seem to use it in practice. I mention it because it is interesting and you may want to try it.
I like the theory of this as well, but in practice it doesn't seem to work so well for me.
If, from LR, I open an image as a smart object.. Then click 'Convert to Linked', it wants to actually save
the file as the original [DNG] filename, but the original directory isn't automatically in the dialog.. And to make matters more uncomfortable, when getting to the original directory it wants to overwrite the original - something that I don't feel comfortable doing.
I'm not sure if it would be the same file if overwritten, but I'm not very keen on finding out if it does/is.
Maybe this is something Adobe needs to flesh out, as there is almost
a seamless way to go from LR to PS and back to LR, etc.. Close, but no cigar - just yet.