| Message ID | E1r0JMB-00CTyJ-08@rmk-PC.armlinux.org.uk (mailing list archive) |
|---|---|
| State | RFC, archived |
| Headers | show |
| Series | Initial cleanups for vCPU hotplug | expand |
On 11/7/23 20:30, Russell King (Oracle) wrote: > From: James Morse <james.morse@arm.com> > > Now that GENERIC_CPU_DEVICES calls arch_register_cpu(), which can be > overridden by the arch code, switch over to this to allow common code > to choose when the register_cpu() call is made. > > This allows topology_init() to be removed. > > This is an intermediate step to the logic being moved to drivers/acpi, > where GENERIC_CPU_DEVICES will do the work when booting with acpi=off. > > This is a subtle change. Originally: > - on boot, topology_init() would have marked present CPUs that > io_master() is true for as hotplug-incapable. > - if a CPU is hotplugged that is an io_master(), it can later be > hot-unplugged. > > The new behaviour is that any CPU that io_master() is true for will > now always be marked as hotplug-incapable, thus even if it was > hotplugged, it can no longer be hot-unplugged. > > This patch also has the effect of moving the registration of CPUs from > subsys to driver core initialisation, prior to any initcalls running. > > Signed-off-by: James Morse <james.morse@arm.com> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> > --- > Changes since RFC v2: > * Explain the change in behaviour in the patch description > (highlighted by Jonathan Cameron - thanks.) Add note about > initialisation order change. > --- > arch/loongarch/Kconfig | 1 + > arch/loongarch/kernel/topology.c | 29 ++--------------------------- > 2 files changed, 3 insertions(+), 27 deletions(-) > Reviewed-by: Gavin Shan <gshan@redhat.com>
On Tue, 07 Nov 2023 10:30:51 +0000 Russell King <rmk+kernel@armlinux.org.uk> wrote: > From: James Morse <james.morse@arm.com> > > Now that GENERIC_CPU_DEVICES calls arch_register_cpu(), which can be > overridden by the arch code, switch over to this to allow common code > to choose when the register_cpu() call is made. > > This allows topology_init() to be removed. > > This is an intermediate step to the logic being moved to drivers/acpi, > where GENERIC_CPU_DEVICES will do the work when booting with acpi=off. > > This is a subtle change. Originally: > - on boot, topology_init() would have marked present CPUs that > io_master() is true for as hotplug-incapable. > - if a CPU is hotplugged that is an io_master(), it can later be > hot-unplugged. > > The new behaviour is that any CPU that io_master() is true for will > now always be marked as hotplug-incapable, thus even if it was > hotplugged, it can no longer be hot-unplugged. > > This patch also has the effect of moving the registration of CPUs from > subsys to driver core initialisation, prior to any initcalls running. > > Signed-off-by: James Morse <james.morse@arm.com> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 64620e90c12c..632de780a490 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -72,6 +72,7 @@ config LOONGARCH select GENERIC_CLOCKEVENTS select GENERIC_CMOS_UPDATE select GENERIC_CPU_AUTOPROBE + select GENERIC_CPU_DEVICES select GENERIC_ENTRY select GENERIC_GETTIMEOFDAY select GENERIC_IOREMAP if !ARCH_IOREMAP diff --git a/arch/loongarch/kernel/topology.c b/arch/loongarch/kernel/topology.c index ae860fe81536..7dfb46c68f58 100644 --- a/arch/loongarch/kernel/topology.c +++ b/arch/loongarch/kernel/topology.c @@ -10,20 +10,13 @@ #include <acpi/processor.h> -static DEFINE_PER_CPU(struct cpu, cpu_devices); - #ifdef CONFIG_HOTPLUG_CPU int arch_register_cpu(int cpu) { - int ret; struct cpu *c = &per_cpu(cpu_devices, cpu); - c->hotpluggable = 1; - ret = register_cpu(c, cpu); - if (ret < 0) - pr_warn("register_cpu %d failed (%d)\n", cpu, ret); - - return ret; + c->hotpluggable = !io_master(cpu); + return register_cpu(c, cpu); } void arch_unregister_cpu(int cpu) @@ -34,21 +27,3 @@ void arch_unregister_cpu(int cpu) unregister_cpu(c); } #endif - -static int __init topology_init(void) -{ - int i, ret; - - for_each_present_cpu(i) { - struct cpu *c = &per_cpu(cpu_devices, i); - - c->hotpluggable = !io_master(i); - ret = register_cpu(c, i); - if (ret < 0) - pr_warn("topology_init: register_cpu %d failed (%d)\n", i, ret); - } - - return 0; -} - -subsys_initcall(topology_init);