============= Changes in v4 ============= * Split arm and arm64 patches so that the change to use reboot_cpu goes into its own separate patch (Russell) * Collected new Acked-by * Rebased on top of v5.6-rc6 * Trimmed the CC list on the cover letter as lists were rejecting it git clone git://linux-arm.org/linux-qy.git -b cpu-hp-cleanup-v4 Older post can be found here ---------------------------- https://lore.kernel.org/lkml/20200223192942.18420-2-qais.yousef@xxxxxxx/ ============= Test Coverage ============= All tests ran with LOCKDEP enabled. Platform: Juno-r2: arm64 ------------------------ * Overnight rcutorture * Overnight locktorture * kexec -f Image --command="$(cat /proc/cmdline) reboot=s[0-5]" * Hibernate to disk (using suspend option) * Userspace hotplug via sysfs * PSCI firemware checker Notes: * Couldn't convince Juno to hibernate using [reboot] or [shutdown] options. Platform: qemu (8 vCPUs) and VM (2 vCPUs): x86_64 ------------------------------------------------- * Overnight rcutorture * Overnight locktorture * Userspace hotplug via sysfs * echo mmiotrace > /sys/kernel/debug/tracing/current_tracer && echo nop > /sys/kernel/debug/tracing/current_tracer * Ran with CONFIG_DEBUG_HOTPLUG_CPU0 and CONFIG_BOOTPARAM_HOTPLUG_CPU0 Notes: * qemu failed to bring cpu0 after offlining. Same behavior observed on vanilla v5.6-rc6. Worked fine on the VM. * mmiotrace successfully brought down all cpus when enabled, then back online again when disabled. Including when cpu0 was offline. * My xen shenanigans are too 'humble' too create environment to test the change in xen yet.. ===================== Original Cover Letter ===================== Using cpu_up/down directly to bring cpus online/offline loses synchronization with sysfs and could suffer from a race similar to what is described in commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and serialization during LPM"). cpu_up/down seem to be more of a internal implementation detail for the cpu subsystem to use to boot up cpus, perform suspend/resume and low level hotplug operations. Users outside of the cpu subsystem would be better using the device core API to bring a cpu online/offline which is the interface used to hotplug memory and other system devices. Several users have already migrated to use the device core API, this series converts the remaining users and hides cpu_up/down from internal users at the end. I noticed this problem while working on a hack to disable offlining a particular CPU but noticed that setting the offline_disabled attribute in the device struct isn't enough because users can easily bypass the device core. While my hack isn't a valid use case but it did highlight the inconsistency in the way cpus are being onlined/offlined and this attempt hopefully improves on this. The first patch introduces new API to {add,remove}_cpu() using device_{online, offline}() with correct locks held and export it. The following 10 patches fix arch users. The remaining 6 patches fix generic code users. Particularly creating a new special exported API for the device core to use instead of cpu_up/down. The last patch removes cpu_up/down from cpu.h and unexport the functions. In some cases where the use of cpu_up/down seemed legitimate, I encapsulated the logic in a higher level - special purposed function; and converted the code to use that instead. CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CC: Tony Luck <tony.luck@xxxxxxxxx> CC: Fenghua Yu <fenghua.yu@xxxxxxxxx> CC: Russell King <linux@xxxxxxxxxxxxxxx> CC: Catalin Marinas <catalin.marinas@xxxxxxx> CC: Michael Ellerman <mpe@xxxxxxxxxxxxxx> CC: "David S. Miller" <davem@xxxxxxxxxxxxx> CC: Helge Deller <deller@xxxxxx> CC: Juergen Gross <jgross@xxxxxxxx> CC: Mark Rutland <mark.rutland@xxxxxxx> CC: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> CC: "Paul E. McKenney" <paulmck@xxxxxxxxxx> CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> CC: xen-devel@xxxxxxxxxxxxxxxxxxxx CC: linux-parisc@xxxxxxxxxxxxxxx CC: sparclinux@xxxxxxxxxxxxxxx CC: linuxppc-dev@xxxxxxxxxxxxxxxx CC: x86@xxxxxxxxxx CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx CC: linux-ia64@xxxxxxxxxxxxxxx CC: linux-kernel@xxxxxxxxxxxxxxx Qais Yousef (17): cpu: Add new {add,remove}_cpu() functions smp: Create a new function to shutdown nonboot cpus ia64: Replace cpu_down with smp_shutdown_nonboot_cpus() arm: Don't use disable_nonboot_cpus() arm: Use reboot_cpu instead of hardcoding it to 0 arm64: Don't use disable_nonboot_cpus() arm64: Use reboot_cpu instead of hardconding it to 0 arm64: hibernate.c: Create a new function to handle cpu_up(sleep_cpu) x86: Replace cpu_up/down with add/remove_cpu powerpc: Replace cpu_up/down with add/remove_cpu sparc: Replace cpu_up/down with add/remove_cpu parisc: Replace cpu_up/down with add/remove_cpu driver: xen: Replace cpu_up/down with device_online/offline firmware: psci: Replace cpu_up/down with add/remove_cpu torture: Replace cpu_up/down with add/remove_cpu smp: Create a new function to bringup nonboot cpus online cpu: Hide cpu_up/down arch/arm/kernel/reboot.c | 4 +- arch/arm64/kernel/hibernate.c | 13 +-- arch/arm64/kernel/process.c | 4 +- arch/ia64/kernel/process.c | 8 +- arch/parisc/kernel/processor.c | 2 +- arch/powerpc/kexec/core_64.c | 2 +- arch/sparc/kernel/ds.c | 4 +- arch/x86/kernel/topology.c | 22 ++--- arch/x86/mm/mmio-mod.c | 4 +- arch/x86/xen/smp.c | 2 +- drivers/base/cpu.c | 4 +- drivers/firmware/psci/psci_checker.c | 4 +- drivers/xen/cpu_hotplug.c | 2 +- include/linux/cpu.h | 10 +- kernel/cpu.c | 134 ++++++++++++++++++++++++++- kernel/smp.c | 9 +- kernel/torture.c | 9 +- 17 files changed, 172 insertions(+), 65 deletions(-) -- 2.17.1
