lkml.org 
[lkml]   [2019]   [Nov]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 4.19 114/149] UAS: Revert commit 3ae62a42090f ("UAS: fix alignment of scatter/gather segments")
    On Fri, 8 Nov 2019, Greg Kroah-Hartman wrote:

    > On Thu, Nov 07, 2019 at 12:32:45PM +0100, Oliver Neukum wrote:
    > > Am Dienstag, den 05.11.2019, 17:38 +0100 schrieb Greg Kroah-Hartman:
    > > > > > Given this information, perhaps you will decide that the revert is
    > > > > > worthwhile.
    > > > >
    > > > > Damned if I do, damned if I do not.
    > > > > Check for usbip and special case it?
    > > >
    > > > We should be able to do that in the host controller driver for usbip,
    > > > right? What is the symptom if you use a UAS device with usbip and this
    > > > commit?
    > >
    > > Yes, that patch should then also be applied. Then it will work.
    > > Without it, commands will fail, as transfers will end prematurely.
    >
    > Ok, I'm confused now. I just checked, and I really have no idea what
    > needs to be backported anymore. 3ae62a42090f ("UAS: fix alignment of
    > scatter/gather segments") was backported to all of the stable kernels,
    > and now we reverted it.
    >
    > So what else needs to be done here?

    In one sense, nothing needs to be done. 3ae62a42090f was intended to
    fix a long-standing problem with USBIP, but people reported a
    regression in performance. (Admittedly, the report was about the
    correponding change to usb-storage, not the change to uas, but it's
    reasonable to think the effect would be the same.) So in line with the
    no-regressions policy, we only need to revert the commit -- which you
    have already done.

    On the other hand, the long-standing problem in USBIP can be fixed by
    back-porting commit ea44d190764b. But since that commit isn't a
    bug-fix (and since it's rather large), you may question whether it is
    appropriate for the -stable kernel series.

    Alan Stern

    \
     
     \ /
      Last update: 2019-11-08 16:36    [W:4.054 / U:0.200 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site