* [PATCH V2] MIPS: CPU#0 is not hotpluggable @ 2020-07-16 10:40 Huacai Chen 2020-07-25 6:37 ` Huacai Chen 2020-07-26 8:25 ` Thomas Bogendoerfer 0 siblings, 2 replies; 11+ messages in thread From: Huacai Chen @ 2020-07-16 10:40 UTC (permalink / raw) To: Thomas Bogendoerfer Cc: linux-mips, Fuxin Zhang, Zhangjin Wu, Huacai Chen, Jiaxun Yang, Huacai Chen, stable Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices /system/cpu/cpu0/online which confuses some user-space tools. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen <chenhc@lemote.com> --- arch/mips/kernel/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c index cd3e1f8..08ad637 100644 --- a/arch/mips/kernel/topology.c +++ b/arch/mips/kernel/topology.c @@ -20,7 +20,7 @@ static int __init topology_init(void) for_each_present_cpu(i) { struct cpu *c = &per_cpu(cpu_devices, i); - c->hotpluggable = 1; + c->hotpluggable = !!i; ret = register_cpu(c, i); if (ret) printk(KERN_WARNING "topology_init: register_cpu %d " -- 2.7.0 ^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-16 10:40 [PATCH V2] MIPS: CPU#0 is not hotpluggable Huacai Chen @ 2020-07-25 6:37 ` Huacai Chen 2020-07-25 6:49 ` Greg KH 2020-07-26 8:25 ` Thomas Bogendoerfer 2020-07-26 8:25 ` Thomas Bogendoerfer 1 sibling, 2 replies; 11+ messages in thread From: Huacai Chen @ 2020-07-25 6:37 UTC (permalink / raw) To: Thomas Bogendoerfer Cc: open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable Hi, Thomas, What do you think about this patch? Other archs also do the same thing except those support hotplug CPU#0. grep hotpluggable arch -rwI arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = platform_can_hotplug_cpu(cpu); arch/sh/kernel/topology.c: c->hotpluggable = 1; arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; arch/s390/kernel/smp.c: c->hotpluggable = 1; arch/mips/kernel/topology.c: c->hotpluggable = 1; arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, we record its initial state and arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); arch/x86/kernel/topology.c: per_cpu(cpu_devices, num).cpu.hotpluggable = 1; On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > /system/cpu/cpu0/online which confuses some user-space tools. > > Cc: stable@vger.kernel.org > Signed-off-by: Huacai Chen <chenhc@lemote.com> > --- > arch/mips/kernel/topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c > index cd3e1f8..08ad637 100644 > --- a/arch/mips/kernel/topology.c > +++ b/arch/mips/kernel/topology.c > @@ -20,7 +20,7 @@ static int __init topology_init(void) > for_each_present_cpu(i) { > struct cpu *c = &per_cpu(cpu_devices, i); > > - c->hotpluggable = 1; > + c->hotpluggable = !!i; > ret = register_cpu(c, i); > if (ret) > printk(KERN_WARNING "topology_init: register_cpu %d " > -- > 2.7.0 > ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 6:37 ` Huacai Chen @ 2020-07-25 6:49 ` Greg KH 2020-07-25 6:57 ` Huacai Chen 2020-07-26 8:25 ` Thomas Bogendoerfer 1 sibling, 1 reply; 11+ messages in thread From: Greg KH @ 2020-07-25 6:49 UTC (permalink / raw) To: Huacai Chen Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > Hi, Thomas, > > What do you think about this patch? Other archs also do the same thing > except those support hotplug CPU#0. > > grep hotpluggable arch -rwI > arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); > arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); > arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; > arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { > arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = > platform_can_hotplug_cpu(cpu); > arch/sh/kernel/topology.c: c->hotpluggable = 1; > arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable > arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; > arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; > arch/s390/kernel/smp.c: c->hotpluggable = 1; > arch/mips/kernel/topology.c: c->hotpluggable = 1; > arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, > we record its initial state and > arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); > arch/x86/kernel/topology.c: per_cpu(cpu_devices, > num).cpu.hotpluggable = 1; > > On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > > /system/cpu/cpu0/online which confuses some user-space tools. What userspace tools are confused by this? They should be able to handle a cpu not being able to be removed, right? > > > > Cc: stable@vger.kernel.org > > Signed-off-by: Huacai Chen <chenhc@lemote.com> > > --- > > arch/mips/kernel/topology.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c > > index cd3e1f8..08ad637 100644 > > --- a/arch/mips/kernel/topology.c > > +++ b/arch/mips/kernel/topology.c > > @@ -20,7 +20,7 @@ static int __init topology_init(void) > > for_each_present_cpu(i) { > > struct cpu *c = &per_cpu(cpu_devices, i); > > > > - c->hotpluggable = 1; > > + c->hotpluggable = !!i; Seems to be the same as what xtensa did, so it's probably not a big deal. thanks, greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 6:49 ` Greg KH @ 2020-07-25 6:57 ` Huacai Chen 2020-07-25 7:45 ` Greg KH 0 siblings, 1 reply; 11+ messages in thread From: Huacai Chen @ 2020-07-25 6:57 UTC (permalink / raw) To: Greg KH Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable Hi Greg, On Sat, Jul 25, 2020 at 2:49 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > > Hi, Thomas, > > > > What do you think about this patch? Other archs also do the same thing > > except those support hotplug CPU#0. > > > > grep hotpluggable arch -rwI > > arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); > > arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); > > arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; > > arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { > > arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = > > platform_can_hotplug_cpu(cpu); > > arch/sh/kernel/topology.c: c->hotpluggable = 1; > > arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable > > arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; > > arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; > > arch/s390/kernel/smp.c: c->hotpluggable = 1; > > arch/mips/kernel/topology.c: c->hotpluggable = 1; > > arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, > > we record its initial state and > > arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); > > arch/x86/kernel/topology.c: per_cpu(cpu_devices, > > num).cpu.hotpluggable = 1; > > > > On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > > > > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > > > /system/cpu/cpu0/online which confuses some user-space tools. > > What userspace tools are confused by this? They should be able to > handle a cpu not being able to be removed, right? It causes ltp's "hotplug" test fails, and ltp considers CPUs with a "online" node be hotpluggable. > > > > > > > > Cc: stable@vger.kernel.org > > > Signed-off-by: Huacai Chen <chenhc@lemote.com> > > > --- > > > arch/mips/kernel/topology.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c > > > index cd3e1f8..08ad637 100644 > > > --- a/arch/mips/kernel/topology.c > > > +++ b/arch/mips/kernel/topology.c > > > @@ -20,7 +20,7 @@ static int __init topology_init(void) > > > for_each_present_cpu(i) { > > > struct cpu *c = &per_cpu(cpu_devices, i); > > > > > > - c->hotpluggable = 1; > > > + c->hotpluggable = !!i; > > Seems to be the same as what xtensa did, so it's probably not a big > deal. > > thanks, > > greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 6:57 ` Huacai Chen @ 2020-07-25 7:45 ` Greg KH 2020-07-25 8:29 ` Huacai Chen 0 siblings, 1 reply; 11+ messages in thread From: Greg KH @ 2020-07-25 7:45 UTC (permalink / raw) To: Huacai Chen Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote: > Hi Greg, > > On Sat, Jul 25, 2020 at 2:49 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > > > On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > > > Hi, Thomas, > > > > > > What do you think about this patch? Other archs also do the same thing > > > except those support hotplug CPU#0. > > > > > > grep hotpluggable arch -rwI > > > arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); > > > arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); > > > arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; > > > arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { > > > arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = > > > platform_can_hotplug_cpu(cpu); > > > arch/sh/kernel/topology.c: c->hotpluggable = 1; > > > arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable > > > arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; > > > arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; > > > arch/s390/kernel/smp.c: c->hotpluggable = 1; > > > arch/mips/kernel/topology.c: c->hotpluggable = 1; > > > arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, > > > we record its initial state and > > > arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); > > > arch/x86/kernel/topology.c: per_cpu(cpu_devices, > > > num).cpu.hotpluggable = 1; > > > > > > On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > > > > > > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > > > > /system/cpu/cpu0/online which confuses some user-space tools. > > > > What userspace tools are confused by this? They should be able to > > handle a cpu not being able to be removed, right? > It causes ltp's "hotplug" test fails, and ltp considers CPUs with a > "online" node be hotpluggable. Is that always true? ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 7:45 ` Greg KH @ 2020-07-25 8:29 ` Huacai Chen 2020-07-25 8:57 ` Greg KH 0 siblings, 1 reply; 11+ messages in thread From: Huacai Chen @ 2020-07-25 8:29 UTC (permalink / raw) To: Greg KH Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable Hi, Greg, On Sat, Jul 25, 2020 at 3:45 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote: > > Hi Greg, > > > > On Sat, Jul 25, 2020 at 2:49 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > > > > > On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > > > > Hi, Thomas, > > > > > > > > What do you think about this patch? Other archs also do the same thing > > > > except those support hotplug CPU#0. > > > > > > > > grep hotpluggable arch -rwI > > > > arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); > > > > arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); > > > > arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; > > > > arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { > > > > arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = > > > > platform_can_hotplug_cpu(cpu); > > > > arch/sh/kernel/topology.c: c->hotpluggable = 1; > > > > arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable > > > > arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; > > > > arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; > > > > arch/s390/kernel/smp.c: c->hotpluggable = 1; > > > > arch/mips/kernel/topology.c: c->hotpluggable = 1; > > > > arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, > > > > we record its initial state and > > > > arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); > > > > arch/x86/kernel/topology.c: per_cpu(cpu_devices, > > > > num).cpu.hotpluggable = 1; > > > > > > > > On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > > > > > > > > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > > > > > /system/cpu/cpu0/online which confuses some user-space tools. > > > > > > What userspace tools are confused by this? They should be able to > > > handle a cpu not being able to be removed, right? > > It causes ltp's "hotplug" test fails, and ltp considers CPUs with a > > "online" node be hotpluggable. > > Is that always true? Yes, someone who meet the same problem report a bug to LTP, and LTP maintainer said that this should be fixed in kernel. Huacai ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 8:29 ` Huacai Chen @ 2020-07-25 8:57 ` Greg KH 2020-07-26 2:17 ` Jiaxun Yang 0 siblings, 1 reply; 11+ messages in thread From: Greg KH @ 2020-07-25 8:57 UTC (permalink / raw) To: Huacai Chen Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable On Sat, Jul 25, 2020 at 04:29:28PM +0800, Huacai Chen wrote: > Hi, Greg, > > On Sat, Jul 25, 2020 at 3:45 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > > > On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote: > > > Hi Greg, > > > > > > On Sat, Jul 25, 2020 at 2:49 PM Greg KH <gregkh@linuxfoundation.org> wrote: > > > > > > > > On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > > > > > Hi, Thomas, > > > > > > > > > > What do you think about this patch? Other archs also do the same thing > > > > > except those support hotplug CPU#0. > > > > > > > > > > grep hotpluggable arch -rwI > > > > > arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); > > > > > arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); > > > > > arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; > > > > > arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { > > > > > arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = > > > > > platform_can_hotplug_cpu(cpu); > > > > > arch/sh/kernel/topology.c: c->hotpluggable = 1; > > > > > arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable > > > > > arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; > > > > > arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; > > > > > arch/s390/kernel/smp.c: c->hotpluggable = 1; > > > > > arch/mips/kernel/topology.c: c->hotpluggable = 1; > > > > > arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, > > > > > we record its initial state and > > > > > arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); > > > > > arch/x86/kernel/topology.c: per_cpu(cpu_devices, > > > > > num).cpu.hotpluggable = 1; > > > > > > > > > > On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: > > > > > > > > > > > > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > > > > > > /system/cpu/cpu0/online which confuses some user-space tools. > > > > > > > > What userspace tools are confused by this? They should be able to > > > > handle a cpu not being able to be removed, right? > > > It causes ltp's "hotplug" test fails, and ltp considers CPUs with a > > > "online" node be hotpluggable. > > > > Is that always true? > Yes, someone who meet the same problem report a bug to LTP, and LTP > maintainer said that this should be fixed in kernel. So the action _always_ has to succeed and can never return an error? That feels wrong even for normal systems. thanks, greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 8:57 ` Greg KH @ 2020-07-26 2:17 ` Jiaxun Yang 0 siblings, 0 replies; 11+ messages in thread From: Jiaxun Yang @ 2020-07-26 2:17 UTC (permalink / raw) To: Greg KH, Huacai Chen Cc: Thomas Bogendoerfer, open list:MIPS, Fuxin Zhang, Zhangjin Wu, stable 在 2020/7/25 下午4:57, Greg KH 写道: > On Sat, Jul 25, 2020 at 04:29:28PM +0800, Huacai Chen wrote: >> Hi, Greg, >> >> On Sat, Jul 25, 2020 at 3:45 PM Greg KH <gregkh@linuxfoundation.org> wrote: >>> On Sat, Jul 25, 2020 at 02:57:31PM +0800, Huacai Chen wrote: >>>> Hi Greg, >>>> >>>> On Sat, Jul 25, 2020 at 2:49 PM Greg KH <gregkh@linuxfoundation.org> wrote: >>>>> On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: >>>>>> Hi, Thomas, >>>>>> >>>>>> What do you think about this patch? Other archs also do the same thing >>>>>> except those support hotplug CPU#0. >>>>>> >>>>>> grep hotpluggable arch -rwI >>>>>> arch/riscv/kernel/setup.c: cpu->hotpluggable = cpu_has_hotplug(i); >>>>>> arch/powerpc/kernel/sysfs.c: BUG_ON(!c->hotpluggable); >>>>>> arch/powerpc/kernel/sysfs.c: c->hotpluggable = 1; >>>>>> arch/powerpc/kernel/sysfs.c: if (cpu_online(cpu) || c->hotpluggable) { >>>>>> arch/arm/kernel/setup.c: cpuinfo->cpu.hotpluggable = >>>>>> platform_can_hotplug_cpu(cpu); >>>>>> arch/sh/kernel/topology.c: c->hotpluggable = 1; >>>>>> arch/ia64/kernel/topology.c: * CPEI target, then it is hotpluggable >>>>>> arch/ia64/kernel/topology.c: sysfs_cpus[num].cpu.hotpluggable = 1; >>>>>> arch/xtensa/kernel/setup.c: cpu->hotpluggable = !!i; >>>>>> arch/s390/kernel/smp.c: c->hotpluggable = 1; >>>>>> arch/mips/kernel/topology.c: c->hotpluggable = 1; >>>>>> arch/arm64/kernel/cpuinfo.c: * In case the boot CPU is hotpluggable, >>>>>> we record its initial state and >>>>>> arch/arm64/kernel/setup.c: cpu->hotpluggable = cpu_can_disable(i); >>>>>> arch/x86/kernel/topology.c: per_cpu(cpu_devices, >>>>>> num).cpu.hotpluggable = 1; >>>>>> >>>>>> On Thu, Jul 16, 2020 at 6:38 PM Huacai Chen <chenhc@lemote.com> wrote: >>>>>>> Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices >>>>>>> /system/cpu/cpu0/online which confuses some user-space tools. >>>>> What userspace tools are confused by this? They should be able to >>>>> handle a cpu not being able to be removed, right? >>>> It causes ltp's "hotplug" test fails, and ltp considers CPUs with a >>>> "online" node be hotpluggable. >>> Is that always true? >> Yes, someone who meet the same problem report a bug to LTP, and LTP >> maintainer said that this should be fixed in kernel. > So the action _always_ has to succeed and can never return an error? > That feels wrong even for normal systems. If that returns error then it means kernel's hotplug function is not working as expected. Thus, LTP as a testsuit will consider the error as a indicator of malfunction kernel. Thanks - Jiaxun > > thanks, > > greg k-h ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-25 6:37 ` Huacai Chen 2020-07-25 6:49 ` Greg KH @ 2020-07-26 8:25 ` Thomas Bogendoerfer 2020-07-26 11:30 ` Jiaxun Yang 1 sibling, 1 reply; 11+ messages in thread From: Thomas Bogendoerfer @ 2020-07-26 8:25 UTC (permalink / raw) To: Huacai Chen; +Cc: open list:MIPS, Fuxin Zhang, Zhangjin Wu, Jiaxun Yang, stable On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: > Hi, Thomas, > > What do you think about this patch? Other archs also do the same thing > except those support hotplug CPU#0. I'm ok with the patch, I'm just wondering if this is a hardware or software limitation. If it's the latter, what needs to be done to support it ? Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-26 8:25 ` Thomas Bogendoerfer @ 2020-07-26 11:30 ` Jiaxun Yang 0 siblings, 0 replies; 11+ messages in thread From: Jiaxun Yang @ 2020-07-26 11:30 UTC (permalink / raw) To: Thomas Bogendoerfer, Huacai Chen Cc: open list:MIPS, Fuxin Zhang, Zhangjin Wu, stable 在 2020/7/26 下午4:25, Thomas Bogendoerfer 写道: > On Sat, Jul 25, 2020 at 02:37:52PM +0800, Huacai Chen wrote: >> Hi, Thomas, >> >> What do you think about this patch? Other archs also do the same thing >> except those support hotplug CPU#0. > I'm ok with the patch, I'm just wondering if this is a hardware or > software limitation. If it's the latter, what needs to be done to > support it ? It should be a software limitation, x86 have already deal with that [1]. But there is no reason to spend extra effort on CPU0 hotplug. I don't think any user is expecting this feature. Thanks. [1]: https://events.static.linuxfound.org/sites/events/files/lcjpcojp13_fenghua.pdf - Jiaxun > > Thomas. > ^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH V2] MIPS: CPU#0 is not hotpluggable 2020-07-16 10:40 [PATCH V2] MIPS: CPU#0 is not hotpluggable Huacai Chen 2020-07-25 6:37 ` Huacai Chen @ 2020-07-26 8:25 ` Thomas Bogendoerfer 1 sibling, 0 replies; 11+ messages in thread From: Thomas Bogendoerfer @ 2020-07-26 8:25 UTC (permalink / raw) To: Huacai Chen Cc: linux-mips, Fuxin Zhang, Zhangjin Wu, Huacai Chen, Jiaxun Yang, stable On Thu, Jul 16, 2020 at 06:40:23PM +0800, Huacai Chen wrote: > Now CPU#0 is not hotpluggable on MIPS, so prevent to create /sys/devices > /system/cpu/cpu0/online which confuses some user-space tools. > > Cc: stable@vger.kernel.org > Signed-off-by: Huacai Chen <chenhc@lemote.com> > --- > arch/mips/kernel/topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) applied to mips-next. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ] ^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2020-07-26 11:30 UTC | newest] Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-16 10:40 [PATCH V2] MIPS: CPU#0 is not hotpluggable Huacai Chen 2020-07-25 6:37 ` Huacai Chen 2020-07-25 6:49 ` Greg KH 2020-07-25 6:57 ` Huacai Chen 2020-07-25 7:45 ` Greg KH 2020-07-25 8:29 ` Huacai Chen 2020-07-25 8:57 ` Greg KH 2020-07-26 2:17 ` Jiaxun Yang 2020-07-26 8:25 ` Thomas Bogendoerfer 2020-07-26 11:30 ` Jiaxun Yang 2020-07-26 8:25 ` Thomas Bogendoerfer
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