Re: [Bug #14015] pty regressed again, breaking expect and gcc's testsuite

Rafael J. Wysocki
2009-09-01T18:42:07Z

On Tuesday 01 September 2009, Mikael Pettersson wrote:
> Mikael Pettersson writes:
> > Rafael J. Wysocki writes:
> > > On Saturday 29 August 2009, Mikael Pettersson wrote:
> > > > Mikael Pettersson writes:
> > > > > Rafael J. Wysocki writes:
> > > > > > On Thursday 27 August 2009, Mikael Pettersson wrote:
> > > > > > > On Tue, 25 Aug 2009 22:34:53 +0200 (CEST), Rafael J. Wysocki wrote:
> > > > > > > > The following bug entry is on the current list of known regressions
> > > > > > > > from 2.6.30. Please verify if it still should be listed and let me know
> > > > > > > > (either way).
> > > > > > > >
> > > > > > > >
> > > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=3D14015
> > > > > > > > Subject : pty regressed again, breaking expect and gcc's testsuite
> > > > > > > > Submitter : Mikael Pettersson <mikpe@it.uu.se>
> > > > > > > > Date : 2009-08-14 23:41 (12 days old)
> > > > > > > > References : http://marc.info/?l=3Dlinux-kernel&m=3D125029329805643&w=3D4
> > > > > > >
> > > > > > > Not fixed. With 2.6.31-rc7 I'm still seeing repeatable testsuite
> > > > > > > failures on powerpc64. Reverting to 2.6.30 makes the failures go away.
> > > > > >
> > > > > > Thanks for the update.
> > > > > >
> > > > > > I guess 2.6.31-rc8 doesn't make any difference, does it?
> > > > >
> > > > > I've scheduled a number of gcc bootstraps and testsuite runs
> > > > > with -rc8 on x86, powerpc64, and arm. I'll post an update in
> > > > > a day or so.
> > > >
> > > > 2.6.31-rc8 results in bogus testsuite failures on all three platforms.
> > >
> > > That may be a result of the known inotify borkage in -rc8 that has been fixed
> > > in the current Linus' tree.
> >
> > No, it's the same old semi-random pty breakage. My kernels are built
> > without inotify.
> >
> > A bisection has identified Alan's
> >
> > pty: Rework the pty layer to use the normal buffering logic
> > d945cb9cce20ac7143c2de8d88b187f62db99bdc
> >
> > as the culprit. This patch introduces a massive number of bogus
> > failures in the gcc testsuite. Subsequent pty/tty patches do fix
> > most of those failures, but clearly not all.
>
> Starting with 2.6.31-rc8 and reverting
>
> 85dfd81dc57e8183a277ddd7a56aa65c96f3f487 pty: fix data loss when stopped (^S/^Q)
> d945cb9cce20ac7143c2de8d88b187f62db99bdc pty: Rework the pty layer to use the normal buffering logic
>
> in that order gives me a kernel that works on both x86 and powerpc64.
>
> So the bug is definitely limited to the pty buffering logic change.

Thanks a lot for this information, adding somme CCs to the list.

Best,
Rafael