Hi Thomas
On 11/25/19 11:27, Qais Yousef wrote:
> Changes in v2:
> * Add 2 new patches that create smp_shutdown_nonboot_cpus() to be used
> in machine_shutdown() in ia64, arm and arm64
> * Use proper kernel-doc for the newly introduced functions
> * Renamed a function
> * Removed a stale comment in a function
> * Rebased on top of 5.4-rc8
>
> git clone git://linux-arm.org/linux-qy.git -b cpu-hp-cleanup-v2
I want to spin v3 to address Russel's comments. If you have any feedback it'd
be great to have them before I spin v3.
Thanks
--
Qais Yousef
>
> 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 8 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.
>
> I did re-run the rcu torture, lock torture and psci checker tests and no
> problem was noticed. I did perform build tests on all arch affected except for
> parisc.
>
> Hopefully I got the CC list right for all the patches. Apologies in advance if
> some people were omitted from some patches but they should have been CCed.
>
> CC: Armijn Hemel <[email protected]>
> CC: Benjamin Herrenschmidt <[email protected]>
> CC: Bjorn Helgaas <[email protected]>
> CC: Borislav Petkov <[email protected]>
> CC: Boris Ostrovsky <[email protected]>
> CC: Catalin Marinas <[email protected]>
> CC: Christophe Leroy <[email protected]>
> CC: Daniel Lezcano <[email protected]>
> CC: Davidlohr Bueso <[email protected]>
> CC: "David S. Miller" <[email protected]>
> CC: Eiichi Tsukata <[email protected]>
> CC: Enrico Weigelt <[email protected]>
> CC: Fenghua Yu <[email protected]>
> CC: Greg Kroah-Hartman <[email protected]>
> CC: Helge Deller <[email protected]>
> CC: "H. Peter Anvin" <[email protected]>
> CC: Ingo Molnar <[email protected]>
> CC: "James E.J. Bottomley" <[email protected]>
> CC: James Morse <[email protected]>
> CC: Jiri Kosina <[email protected]>
> CC: Josh Poimboeuf <[email protected]>
> CC: Josh Triplett <[email protected]>
> CC: Juergen Gross <[email protected]>
> CC: Lorenzo Pieralisi <[email protected]>
> CC: Mark Rutland <[email protected]>
> CC: Michael Ellerman <[email protected]>
> CC: Nadav Amit <[email protected]>
> CC: Nicholas Piggin <[email protected]>
> CC: "Paul E. McKenney" <[email protected]>
> CC: Paul Mackerras <[email protected]>
> CC: Pavankumar Kondeti <[email protected]>
> CC: "Peter Zijlstra (Intel)" <[email protected]>
> CC: "Rafael J. Wysocki" <[email protected]>
> CC: Ram Pai <[email protected]>
> CC: Richard Fontana <[email protected]>
> CC: Russell King <[email protected]>
> CC: Sakari Ailus <[email protected]>
> CC: Stefano Stabellini <[email protected]>
> CC: Steve Capper <[email protected]>
> CC: Thiago Jung Bauermann <[email protected]>
> CC: Thomas Gleixner <[email protected]>
> CC: Tony Luck <[email protected]>
> CC: Will Deacon <[email protected]>
> CC: Zhenzhong Duan <[email protected]>
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
>
>
> Qais Yousef (14):
> smp: create a new function to shutdown nonboot cpus
> ia64: Replace cpu_down with smp_shutdown_nonboot_cpus()
> arm: arm64: Don't use disable_nonboot_cpus()
> arm64: hibernate.c: create a new function to handle cpu_up(sleep_cpu)
> x86: Replace cpu_up/down with devcie_online/offline
> powerpc: Replace cpu_up/down with device_online/offline
> sparc: Replace cpu_up/down with device_online/offline
> parisc: Replace cpu_up/down with device_online/offline
> driver: base: cpu: export device_online/offline
> driver: xen: Replace cpu_up/down with device_online/offline
> firmware: psci: Replace cpu_up/down with device_online/offline
> torture: Replace cpu_up/down with device_online/offline
> 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 | 4 +-
> arch/powerpc/kernel/machine_kexec_64.c | 4 +-
> arch/sparc/kernel/ds.c | 8 ++-
> arch/x86/kernel/topology.c | 4 +-
> arch/x86/mm/mmio-mod.c | 8 ++-
> arch/x86/xen/smp.c | 4 +-
> drivers/base/core.c | 4 ++
> drivers/base/cpu.c | 4 +-
> drivers/firmware/psci/psci_checker.c | 6 +-
> drivers/xen/cpu_hotplug.c | 2 +-
> include/linux/cpu.h | 8 ++-
> kernel/cpu.c | 85 ++++++++++++++++++++++++--
> kernel/smp.c | 9 +--
> kernel/torture.c | 15 +++--
> 18 files changed, 143 insertions(+), 51 deletions(-)
>
> --
> 2.17.1
>
