Currently the patch module calls kpatch_unregister in the patch module
exit path. If the activeness safety check fails in kpatch_unregister,
it's too late for the patch module to stop exiting, so all it can do is
panic.
Prevent this scenario by requiring the user to disable the patch module
via sysfs before allowing the module to be unloaded. The sysfs write
will fail if the activeness safety check fails. An rmmod will fail if
the patch is still enabled.
Also add support for this new unloading model in "kpatch unload".
The kpatch utility is now user friendly enough that it can be used
instead of direct insmods. We should encourage people to use it, since
we will soon be adding user space functionality above and beyond
insmod/rmmod when loading and unloading.
Try to be more consistent with the terminology. In various places we
call it a "hotpatch module", "hot patch module", or "patch module". How
about we just call it a "patch module" everywhere?
kpatch-build is outgrowing the kpatch script and probably is a better
fit as its own utility instead of being wrapped by kpatch. Install
kpatch-build into /usr/local/bin, remove the kpatch wrapper around it,
and update the README accordingly.
- move license to bottom
- clarify dependencies and installation procedure
- move gotchas section to installation section
- move status section to intro
- add more information about how it works
Build and install the kpatch core module with make and make install,
rather than building it every time with kpatch build.
The only downside to this approach is that the user has to make and make
install kpatch every time they get a new kernel. But this is only
temporary, until the kpatch module is delivered in an RPM.
Seth Jennings
Josh Poimboeuf
Seth Jennings