1
linux/arch
Will Deacon 534be1d5a2 ARM: 6194/1: change definition of cpu_relax() for ARM11MPCore
Linux expects that if a CPU modifies a memory location, then that
modification will eventually become visible to other CPUs in the system.

On an ARM11MPCore processor, loads are prioritised over stores so it is
possible for a store operation to be postponed if a polling loop immediately
follows it. If the variable being polled indirectly depends on the outstanding
store [for example, another CPU may be polling the variable that is pending
modification] then there is the potential for deadlock if interrupts are
disabled. This deadlock occurs in the KGDB testsuire when executing on an
SMP ARM11MPCore configuration.

This patch changes the definition of cpu_relax() to smp_mb() for ARMv6 cores,
forcing a flushing of the write buffer on SMP systems before the next load
takes place. If the Kernel is not compiled for SMP support, this will expand
to a barrier() as before.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2010-07-01 10:13:52 +01:00
..
alpha alpha: Detect Super IO chip, no IDE on Avanti, enable EPP19 2010-06-15 14:19:08 -04:00
arm ARM: 6194/1: change definition of cpu_relax() for ARM11MPCore 2010-07-01 10:13:52 +01:00
avr32 avr32: use asm-generic/scatterlist.h 2010-05-27 09:12:54 -07:00
blackfin blackfin: use use asm-generic/scatterlist.h 2010-05-27 09:12:55 -07:00
cris Merge branch 'for-linus' of git://www.jni.nu/cris 2010-06-01 08:51:25 -07:00
frv FRV: Reinstate null behaviour for the GDB remote protocol 'p' command 2010-06-09 12:42:44 -07:00
h8300 Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
ia64 KVM: ia64: Add missing spin_unlock in kvm_arch_hardware_enable() 2010-06-09 18:48:40 +03:00
m32r m32r: invoke oom-killer from page fault 2010-06-04 15:21:44 -07:00
m68k Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k 2010-05-27 10:19:19 -07:00
m68knommu Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
microblaze Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2010-06-11 14:15:44 -07:00
mips Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
mn10300 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2010-06-11 14:15:44 -07:00
parisc Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
powerpc Merge branch 'merge' of git://git.secretlab.ca/git/linux-2.6 2010-06-27 07:30:25 -07:00
s390 [S390] Update default configuration. 2010-06-08 18:58:23 +02:00
score asm-generic: remove ISA_DMA_THRESHOLD in scatterlist.h 2010-05-27 09:12:54 -07:00
sh arch/sh/mm: Eliminate a double lock 2010-06-21 13:46:53 +09:00
sparc Merge branch 'for-35' of git://repo.or.cz/linux-kbuild 2010-06-01 08:55:52 -07:00
um um: os-linux/mem.c needs sys/stat.h 2010-06-29 15:29:32 -07:00
x86 Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-06-28 12:24:43 -07:00
xtensa xtensa: invoke oom-killer from page fault 2010-06-04 15:21:44 -07:00
.gitignore
Kconfig hw-breakpoints: Separate constraint space for data and instruction breakpoints 2010-05-01 04:32:11 +02:00