lkml.org 
[lkml]   [2007]   [Apr]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/8] Use process freezer for cpu-hotplug

    * Nathan Lynch <ntl@pobox.com> wrote:

    > > - raw_notifier_call_chain(&cpu_chain, CPU_LOCK_ACQUIRE, hcpu);
    > > + if (freeze_processes(FE_HOTPLUG_CPU)) {
    > > + thaw_processes(FE_HOTPLUG_CPU);
    > > + return -EBUSY;
    > > + }
    > > +
    >
    > If I'm understanding correctly, this will cause
    >
    > # echo 0 > /sys/devices/system/cpu/cpuX/online
    >
    > to sometimes fail, and userspace is expected to try again? This will
    > break existing applications.
    >
    > Perhaps drivers/base/cpu.c:store_online should retry as long as
    > cpu_up/down return -EBUSY. That would avoid a userspace-visible
    > interface change.

    yeah. I'd even suggest a freeze_processes_nofail() API instead, that
    does this internally, without burdening the callsites. (and once the
    freezer becomes complete then freeze_processes_nofail() ==
    freeze_processes())

    Ingo
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-04-06 19:37    [W:0.023 / U:271.788 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site