• Linus Torvalds's avatar
    init: rename and re-order boot_cpu_state_init() · b7722f4a
    Linus Torvalds authored
    commit b5b1404d
    This is purely a preparatory patch for upcoming changes during the 4.19
    merge window.
    We have a function called "boot_cpu_state_init()" that isn't really
    about the bootup cpu state: that is done much earlier by the similarly
    named "boot_cpu_init()" (note lack of "state" in name).
    This function initializes some hotplug CPU state, and needs to run after
    the percpu data has been properly initialized.  It even has a comment to
    that effect.
    Except it _doesn't_ actually run after the percpu data has been properly
    initialized.  On x86 it happens to do that, but on at least arm and
    arm64, the percpu base pointers are initialized by the arch-specific
    'smp_prepare_boot_cpu()' hook, which ran _after_ boot_cpu_state_init().
    This had some unexpected results, and in particular we have a patch
    pending for the merge window that did the obvious cleanup of using
    'this_cpu_write()' in the cpu hotplug init code:
      -       per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
      +       this_cpu_write(cpuhp_state.state, CPUHP_ONLINE);
    which is obviously the right thing to do.  Except because of the
    ordering issue, it actually failed miserably and unexpectedly on arm64.
    So this just fixes the ordering, and changes the name of the function to
    be 'boot_cpu_hotplug_init()' to make it obvious that it's about cpu
    hotplug state, because the core CPU state was supposed to have already
    been done earlier.
    Marked for stable, since the (not yet merged) patch that will show this
    problem is marked for stable.
    Reported-by: default avatarVlastimil Babka <vbabka@suse.cz>
    Reported-by: default avatarMian Yousaf Kaukab <yousaf.kaukab@suse.com>
    Suggested-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: stable@kernel.org
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>