| Message ID | 20190823115720.605-6-cristian.marussi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Unify SMP stop generic logic to common code | expand |
> +config ARCH_USE_COMMON_SMP_STOP > + def_bool y if SMP The option belongs into common code and the arch code shoud only select it.
Hi On 8/26/19 4:32 PM, Christoph Hellwig wrote: >> +config ARCH_USE_COMMON_SMP_STOP >> + def_bool y if SMP > > The option belongs into common code and the arch code shoud only > select it. > In fact that was my first approach, but then I noticed that in kernel/ topdir there was no generic Kconfig but only subsystem specific ones: Kconfig.freezer Kconfig.hz Kconfig.locks Kconfig.preempt while instead looking into archs top level Kconfig, beside the usual arch/Kconfig selects, I could find this similar sort of "reversed" approach in which the arch defined and selected a CONFIG which was indeed then used only in common code like in: 20:37 $ egrep -R ARCH_HAS_CACHE_LINE_SIZE . ./arch/arc/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE ./arch/x86/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE ./arch/arm64/Kconfig:config ARCH_HAS_CACHE_LINE_SIZE ./include/linux/cache.h:#ifndef CONFIG_ARCH_HAS_CACHE_LINE_SIZE 20:39 $ egrep -R ARCH_HAS_KEXEC_PURGATORY . ./arch/powerpc/Kconfig:config ARCH_HAS_KEXEC_PURGATORY ./arch/x86/Kconfig:config ARCH_HAS_KEXEC_PURGATORY ./arch/s390/Kconfig:config ARCH_HAS_KEXEC_PURGATORY ./arch/s390/purgatory/Makefile:obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += kexec-purgatory.o ./arch/s390/Kbuild:obj-$(CONFIG_ARCH_HAS_KEXEC_PURGATORY) += purgatory/ ./kernel/kexec_file.c: if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY)) so I thought it was an acceptable option and I went for it, not to introduce a new kernel/Kconfig.smp just for this new config option; but in fact I could have missed the real reason underlying these two different choices. Thanks Cristian
On Mon, 26 Aug 2019, Cristian Marussi wrote: > On 8/26/19 4:32 PM, Christoph Hellwig wrote: > > > +config ARCH_USE_COMMON_SMP_STOP > > > + def_bool y if SMP > > > > The option belongs into common code and the arch code shoud only > > select it. > > > > In fact that was my first approach, but then I noticed that in kernel/ topdir > there was no generic Kconfig but only subsystem specific ones: > > Kconfig.freezer Kconfig.hz Kconfig.locks Kconfig.preempt arch/Kconfig Thanks, tglx
Hi On 26/08/2019 23:26, Thomas Gleixner wrote: > On Mon, 26 Aug 2019, Cristian Marussi wrote: >> On 8/26/19 4:32 PM, Christoph Hellwig wrote: >>>> +config ARCH_USE_COMMON_SMP_STOP >>>> + def_bool y if SMP >>> >>> The option belongs into common code and the arch code shoud only >>> select it. >>> >> >> In fact that was my first approach, but then I noticed that in kernel/ topdir >> there was no generic Kconfig but only subsystem specific ones: >> >> Kconfig.freezer Kconfig.hz Kconfig.locks Kconfig.preempt > > arch/Kconfig > Ok I'll move it there in v2. Thanks for the review. Cristian > Thanks, > > tglx >
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3adcec05b1f6..3baa69ca4c55 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -276,6 +276,9 @@ config ARCH_ENABLE_MEMORY_HOTPLUG config SMP def_bool y +config ARCH_USE_COMMON_SMP_STOP + def_bool y if SMP + config KERNEL_MODE_NEON def_bool y diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 018a33e01b0e..473be3c23df7 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -953,33 +953,16 @@ void tick_broadcast(const struct cpumask *mask) } #endif -void smp_send_stop(void) +void arch_smp_cpus_stop_complete(void) { - unsigned long timeout; - - if (num_online_cpus() > 1) { - cpumask_t mask; - - cpumask_copy(&mask, cpu_online_mask); - cpumask_clear_cpu(smp_processor_id(), &mask); - - if (system_state <= SYSTEM_RUNNING) - pr_crit("SMP: stopping secondary CPUs\n"); - smp_cross_call(&mask, IPI_CPU_STOP); - } - - /* Wait up to one second for other CPUs to stop */ - timeout = USEC_PER_SEC; - while (num_online_cpus() > 1 && timeout--) - udelay(1); - - if (num_online_cpus() > 1) - pr_warning("SMP: failed to stop secondary CPUs %*pbl\n", - cpumask_pr_args(cpu_online_mask)); - sdei_mask_local_cpu(); } +void arch_smp_stop_call(cpumask_t *cpus) +{ + smp_cross_call(cpus, IPI_CPU_STOP); +} + #ifdef CONFIG_KEXEC_CORE void crash_smp_send_stop(void) {
Make arm64 use the generic SMP-stop logic provided by common code unified smp_send_stop() function. arm64 smp_send_stop() logic had a bug in it: it failed to consider the online status of the calling CPU when evaluating if any stop message needed to be sent to other CPus at all: this resulted, on a 2-CPUs system, in the failure to stop all cpus if one paniced while starting up, leaving such system in an unexpected lively state. [root@arch ~]# echo 1 > /sys/devices/system/cpu/cpu1/online [root@arch ~]# [ 152.583368] ------------[ cut here ]------------ [ 152.583872] kernel BUG at arch/arm64/kernel/cpufeature.c:852! [ 152.584693] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP [ 152.585228] Modules linked in: [ 152.586040] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0-rc5-00001-gcabd12118c4a-dirty #2 [ 152.586218] Hardware name: Foundation-v8A (DT) [ 152.586478] pstate: 000001c5 (nzcv dAIF -PAN -UAO) [ 152.587260] pc : has_cpuid_feature+0x35c/0x360 [ 152.587398] lr : verify_local_elf_hwcaps+0x6c/0xf0 [ 152.587520] sp : ffff0000118bbf60 [ 152.587605] x29: ffff0000118bbf60 x28: 0000000000000000 [ 152.587784] x27: 0000000000000000 x26: 0000000000000000 [ 152.587882] x25: ffff00001167a010 x24: ffff0000112f59f8 [ 152.587992] x23: 0000000000000000 x22: 0000000000000000 [ 152.588085] x21: ffff0000112ea018 x20: ffff000010fe5518 [ 152.588180] x19: ffff000010ba3f30 x18: 0000000000000036 [ 152.588285] x17: 0000000000000000 x16: 0000000000000000 [ 152.588380] x15: 0000000000000000 x14: ffff80087a821210 [ 152.588481] x13: 0000000000000000 x12: 0000000000000000 [ 152.588599] x11: 0000000000000080 x10: 00400032b5503510 [ 152.588709] x9 : 0000000000000000 x8 : ffff000010b93204 [ 152.588810] x7 : 00000000800001d8 x6 : 0000000000000005 [ 152.588910] x5 : 0000000000000000 x4 : 0000000000000000 [ 152.589021] x3 : 0000000000000000 x2 : 0000000000008000 [ 152.589121] x1 : 0000000000180480 x0 : 0000000000180480 [ 152.589379] Call trace: [ 152.589646] has_cpuid_feature+0x35c/0x360 [ 152.589763] verify_local_elf_hwcaps+0x6c/0xf0 [ 152.589858] check_local_cpu_capabilities+0x88/0x118 [ 152.589968] secondary_start_kernel+0xc4/0x168 [ 152.590530] Code: d53801e0 17ffff58 d5380600 17ffff56 (d4210000) [ 152.592215] ---[ end trace 80ea98416149c87e ]--- [ 152.592734] Kernel panic - not syncing: Attempted to kill the idle task! [ 152.593173] Kernel Offset: disabled [ 152.593501] CPU features: 0x0004,20c02008 [ 152.593678] Memory Limit: none [ 152.594208] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- [root@arch ~]# bash: echo: write error: Input/output error [root@arch ~]# [root@arch ~]# [root@arch ~]# echo HELO HELO Get rid of such bug, switching arm64 to use the common SMP stop code. Reported-by: Dave Martin <Dave.Martin@arm.com> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> --- arch/arm64/Kconfig | 3 +++ arch/arm64/kernel/smp.c | 29 ++++++----------------------- 2 files changed, 9 insertions(+), 23 deletions(-)