aha/arch
Jason Wessel 8097551d9a kgdb,x86: do not set kgdb_single_step on x86
On an SMP system the kgdb_single_step flag has the possibility to
indefinitely hang the system in the case.  Consider the case where,
CPU 1 has the schedule lock and CPU 0 is set to single step, there is
no way for CPU 0 to run another task.

The easy way to observe the problem is to make 2 cpus busy, and run
the kgdb test suite.  You will see that it hangs the system very
quickly.

while [ 1 ] ; do find /proc > /dev/null 2>&1 ; done &
while [ 1 ] ; do find /proc > /dev/null 2>&1 ; done &
echo V1 > /sys/module/kgdbts/parameters/kgdbts

The side effect of this patch is that there is the possibility
to miss a breakpoint in the case that a single step operation
was executed to step over a breakpoint in common code.

The trade off of the missed breakpoint is preferred to
hanging the kernel.  This can be fixed in the future by
using kprobes or another strategy to step over planted
breakpoints with out of line execution.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2009-12-11 08:43:18 -06:00
..
alpha Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
arm Merge branch 'for-linus' of git://gitorious.org/linux-omap-dss2/linux 2009-12-10 21:55:17 -08:00
avr32 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
blackfin Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
cris Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
frv Merge branch 'bkl-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-09 08:07:51 -08:00
h8300 Merge branch 'bkl-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-09 08:07:51 -08:00
ia64 Merge branch 'acpica' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6 2009-12-09 19:57:06 -08:00
m32r Merge branch 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block 2009-12-08 08:19:16 -08:00
m68k Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
m68knommu Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2009-12-09 19:09:42 -08:00
microblaze Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
mips Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
mn10300 Merge branch 'bkl-arch-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-09 08:07:51 -08:00
parisc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
powerpc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
s390 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
score
sh Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2009-12-09 19:43:33 -08:00
sparc Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 19:27:08 -08:00
um
x86 kgdb,x86: do not set kgdb_single_step on x86 2009-12-11 08:43:18 -06:00
xtensa Merge branch 'for-2.6.33' of git://git.kernel.dk/linux-2.6-block 2009-12-08 08:19:16 -08:00
.gitignore
Kconfig Merge branch 'kvm-updates/2.6.33' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2009-12-08 08:02:38 -08:00