On Tue, 31 Jan 2017, Josh Poimboeuf wrote: > On Tue, Jan 31, 2017 at 03:31:39PM +0100, Miroslav Benes wrote: > > On Thu, 19 Jan 2017, Josh Poimboeuf wrote: > > > > > Expose the per-task patch state value so users can determine which tasks > > > are holding up completion of a patching operation. > > > > > > Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com> > > > Reviewed-by: Petr Mladek <pmla...@suse.com> > > > Reviewed-by: Miroslav Benes <mbe...@suse.cz> > > > --- > > > Documentation/filesystems/proc.txt | 18 ++++++++++++++++++ > > > fs/proc/base.c | 15 +++++++++++++++ > > > 2 files changed, 33 insertions(+) > > > > > > diff --git a/Documentation/filesystems/proc.txt > > > b/Documentation/filesystems/proc.txt > > > index 72624a1..85c501b 100644 > > > --- a/Documentation/filesystems/proc.txt > > > +++ b/Documentation/filesystems/proc.txt > > > @@ -44,6 +44,7 @@ Table of Contents > > > 3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file > > > 3.9 /proc/<pid>/map_files - Information about memory mapped files > > > 3.10 /proc/<pid>/timerslack_ns - Task timerslack value > > > + 3.11 /proc/<pid>/patch_state - Livepatch patch operation state > > > > > > 4 Configuring procfs > > > 4.1 Mount options > > > @@ -1886,6 +1887,23 @@ Valid values are from 0 - ULLONG_MAX > > > An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS > > > level > > > permissions on the task specified to change its timerslack_ns value. > > > > > > +3.11 /proc/<pid>/patch_state - Livepatch patch operation state > > > +----------------------------------------------------------------- > > > +When CONFIG_LIVEPATCH is enabled, this file displays the value of the > > > +patch state for the task. > > > + > > > +A value of '-1' indicates that no patch is in transition. > > > + > > > +A value of '0' indicates that a patch is in transition and the task is > > > +unpatched. If the patch is being enabled, then the task hasn't been > > > +patched yet. If the patch is being disabled, then the task has already > > > +been unpatched. > > > + > > > +A value of '1' indicates that a patch is in transition and the task is > > > +patched. If the patch is being enabled, then the task has already been > > > +patched. If the patch is being disabled, then the task hasn't been > > > +unpatched yet. > > > + > > > > Despite my review I thought about this some more. I think the logic make > > sense internally but when exposed it can be confusing. We do not export > > klp_target_state value, so users have to know if a patch is being enabled > > or disabled. Of course, they should know that, but I guess they'd like to > > use an userspace tool for this. Such tool needs to look at > > /proc/<pid>/patch_state to find out which tasks are blocking the > > completion and that is it. No more information anywhere. > > > > We can either export klp_target_state, or change /proc/<pid>/patch_state > > to show only two states - task is in transition (1), task is patched (0). > > > > What do you think? > > Isn't this information already available in > /sys/kernel/livepatch/<patch>/{enabled,transition}?
transition no. That only gives the hint that something is happening with the patch. But yes, enabled is the one I wanted. I don't know how I missed that. Combined with /proc/<pid>/task it is exactly what a tool needs. Miroslav