Messages in this thread | | | Date | Thu, 13 Mar 2014 17:43:35 +0000 | From | Zoltan Kiss <> | Subject | Re: [PATCH net-next v7 4/9] xen-netback: Introduce TX grant mapping |
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On 13/03/14 13:56, Ian Campbell wrote: > On Thu, 2014-03-13 at 13:17 +0000, Zoltan Kiss wrote: >> On 13/03/14 10:33, Ian Campbell wrote: >>> On Thu, 2014-03-06 at 21:48 +0000, Zoltan Kiss wrote: >>> >>>> + netdev_err(vif->dev, >>>> + "Page still granted! Index: %x\n", >>>> + i); >>>> + i = -1; >>> >>> Should there not be a break here? Otherwise don't we restart the for >>> loop from 0 again? If that is intentional then a comment would be very >>> useful. >> Yes, that's intentional, we shouldn't exit this loop until everything is >> unmapped. An i-- would be fine as well. I will put a comment there. > > Yes please do, it's very non-obvious what is going on. I'm almost > inclined to suggest that this is one of the few places where a goto > retry might be appropriate. > > Can you also add a comment saying what is doing the actual unmap work > which we are waiting for here since it is not actually part of the loop. > Might a barrier be needed to ensure we see that work happening? I don't think a barrier is necessary here, if this function ran into !NETBACK_INVALID_HANDLE, it just starts again the checking.
On 13/03/14 13:17, Zoltan Kiss wrote:>> >> [...] >>> + /* Btw. already unmapped? */ >> >> What does this comment mean? Is it a fixme? An indicator that >> xenvif_grant_handle_reset is supposed to handle this case or something >> else? > It comes from the time when xenvif_grant_handle_reset was not a > standalone function. Yes, it refers to the check in the beginning of > that function, and it should go there.
I ended up removing that comment, the error message in the function tells the same.
Zoli
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