No errors thrown when kernel.ftrace_enabled=0 and things don't work

[cormander]

When I do this;

sudo sysctl kernel.ftrace_enabled=0

There are no errors on kpatch insmod, or on the load of any kpatch modules. The symbols don't get patched either, and yet kpatch doesn't report any problems.

It would be just a simple addition to 4f7c587 if you accept commit, that gets and checks the ftrace_enabled symbol in the same way.

I should note that, after ftrace_bug() is called, this happens:

$ cat /proc/sys/kernel/ftrace_enabled
cat: /proc/sys/kernel/ftrace_enabled: No such device

So we could just replace if (ftrace_disabled) with if (!ftrace_enabled), but I think for sanity sake we ought to check both.

I'm happy to write this if you'd like.

[cormander]

7426d53 pushed to my branch ... what can I say? Long weekend.

[jpoimboe]

Closing for now, see #385 for the current ftrace error handling plan.