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

[Mikael Pettersson]

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@xxxxxxxx>
 >  > >  >  > > > 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.
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