Re: [PATCH] fix console change race exposed by CFS


* Jan Luebbe <jluebbe@xxxxxxxxx> wrote:

I'm currenly porting the OpenMoko patchset to 2.6.23-rc8. We are using
psplash and kdrive. When booting, I got an error from psplash about
being unable to switch consoles. Strangely, it was possible to start
kdrive manually. So i set up qemu for kernel debugging, set some
interesting breakpoints and then saw that it was scheduling away
directly after the kill_pid. Then it was quite obvious.

It was triggering every time, on the device and in qemu identically.
Most people testing the RCs probably don't run psplash (or any other
program which sets vt_mode.mode to VT_PROCESS), so it wasn't noticed
earlier.

thx for the description. I did some searching on google.com/codesearch,
and here are some other console apps that make active use of VT_PROCESS:

1diskxwin-2.0.0/X11/programs/Xserver/hw/kdrive/linux/linux.c
usr/include/dev/wscons/wsdisplay_compat_usl.c
busybox-1.01/loginutils/vlock.c
allegro-4.2.2/src/linux/vtswitch.c
tvision/classes/linux/linuxkey.cc
xc/programs/Xserver/hw/xfree86/os-support/pmax/pmax_init.c
aalib-1.4.0/src/aalinuxkbd.c
qt-embedded-opensource-4.0.0-b2/src/gui/embedded/qkbdtty_qws.cpp
mc-4.5.55/src/cons.handler.c
psplash-0.1/psplash-console.c
quakeforge-0.5.5/libs/video/targets/vid_fbdev.c

just in case someone has a regression with any of them, on an older
kernel. To me it appears X should have triggered this too. Perhaps
people dont switch between VGA and X all that frequently anymore ...

Ingo
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