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@xxxxxxx> > --- > 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@xxxxxxxxxxxxxxx > 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@xxxxxxxxxxxxxxx > +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
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