lkml.org 
[lkml]   [2014]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH net-next v5 4/9] xen-netback: Change RX path for mapped SKB fragments
    On 24/02/14 13:49, Zoltan Kiss wrote:
    > On 22/02/14 23:18, Zoltan Kiss wrote:
    >> On 18/02/14 17:45, Ian Campbell wrote:
    >>> On Mon, 2014-01-20 at 21:24 +0000, Zoltan Kiss wrote:
    >>>
    >>> Re the Subject: change how? Perhaps "handle foreign mapped pages on the
    >>> guest RX path" would be clearer.
    >> Ok, I'll do that.
    >>
    >>>
    >>>> RX path need to know if the SKB fragments are stored on pages from
    >>>> another
    >>>> domain.
    >>> Does this not need to be done either before the mapping change or at
    >>> the
    >>> same time? -- otherwise you have a window of a couple of commits where
    >>> things are broken, breaking bisectability.
    >> I can move this to the beginning, to keep bisectability. I've put it
    >> here originally because none of these makes sense without the
    >> previous patches.
    > Well, I gave it a close look: to move this to the beginning as a
    > separate patch I would need to put move a lot of definitions from the
    > first patch to here (ubuf_to_vif helper, xenvif_zerocopy_callback
    > etc.). That would be the best from bisect point of view, but from
    > patch review point of view even worse than now. So the only option I
    > see is to merge this with the first 2 patches, so it will be even bigger.
    Actually I was stupid, we can move this patch earlier and introduce
    stubs for those 2 functions. But for the another two patches (#6 and #8)
    it's still true that we can't move them before, only merge them into the
    main, as they heavily rely on the main patch. #6 is necessary for
    Windows frontends, as they are keen to send too many slots. #8 is quite
    a rare case, happens only if a guest wedge or malicious, and sits on the
    packet.
    So my question is still up: do you prefer perfect bisectability or more
    segmented patches which are not that pain to review?

    > And based on that principle, patch #6 and #8 should be merged there as
    > well, as they solve corner cases introduced by the grant mapping.
    > I don't know how much the bisecting requirements are written in stone.
    > At this moment, all the separate patches compile, but after #2 there
    > are new problems solved in #4, #6 and #8. If someone bisect in the
    > middle of this range and run into these problems, they could quite
    > easily figure out what went wrong looking at the adjacent patches. So
    > I would recommend to keep this current order.
    > What's your opinion?
    >
    > Zoli



    \
     
     \ /
      Last update: 2014-02-24 17:01    [W:5.193 / U:3.316 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site