lkml.org 
[lkml]   [2017]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 2/2] livepatch: force transition process to finish
    On Tue 2017-10-31 12:48:53, Miroslav Benes wrote:
    > If a task sleeps in a set of patched functions uninterruptedly, it could
    > block the whole transition process indefinitely. Thus it may be useful
    > to clear its TIF_PATCH_PENDING to allow the process to finish.
    >
    > Admin can do that now by writing to force sysfs attribute in livepatch
    > sysfs directory. TIF_PATCH_PENDING is then cleared for all tasks and the
    > transition can finish successfully.
    >
    > Important note! Use wisely. Admin must be sure that it is safe to
    > execute such action. This means that it must be checked that by doing so
    > the consistency model guarantees are not violated.
    >
    > Signed-off-by: Miroslav Benes <mbenes@suse.cz>
    > ---
    > Documentation/ABI/testing/sysfs-kernel-livepatch | 10 +++++++++
    > Documentation/livepatch/livepatch.txt | 24 +++++++++++++++------
    > kernel/livepatch/core.c | 27 ++++++++++++++++++++++++
    > kernel/livepatch/transition.c | 25 ++++++++++++++++++++++
    > kernel/livepatch/transition.h | 1 +
    > 5 files changed, 81 insertions(+), 6 deletions(-)
    >
    > diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
    > index 22f6267836c2..105f617008f1 100644
    > --- a/Documentation/ABI/testing/sysfs-kernel-livepatch
    > +++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
    > @@ -42,6 +42,16 @@ Contact: live-patching@vger.kernel.org
    > course of an existing transition. Writing 1 sends a signal to
    > all remaining blocking tasks.
    >
    > +What: /sys/kernel/livepatch/<patch>/force
    > +Date: Oct 2017
    > +KernelVersion: 4.15.0
    > +Contact: live-patching@vger.kernel.org
    > +Description:
    > + A writable attribute that allows administrator to affect the
    > + course of an existing transition. Writing 1 clears
    > + TIF_PATCH_PENDING flag of all tasks and thus forces the tasks to
    > + the patched or unpatched state.
    > +

    NAK. Admin does not have chance to decide if this is safe or not.

    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
    [unhandled content-type:application/pgp-signature]
    \
     
     \ /
      Last update: 2017-11-06 12:11    [W:4.667 / U:0.520 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site