Hi,
在 2026/2/27 01:30, Steven Rostedt 写道:
On Thu, 26 Feb 2026 11:51:53 +0100 (CET)
Miroslav Benes <[email protected]> wrote:
Let me see if there is any way to use notifier and remain below calling
sequence:
ftrace_module_enable
klp_module_coming
blocking_notifier_call_chain_robust(MODULE_STATE_COMING)
blocking_notifier_call_chain(MODULE_STATE_GOING)
klp_module_going
ftrace_release_mod
Both klp and ftrace used module notifiers in the past. We abandoned that
and opted for direct calls due to issues with ordering at the time. I do
not have the list of problems at hand but I remember it was very fragile.
See commits 7dcd182bec27 ("ftrace/module: remove ftrace module
notifier"), 7e545d6eca20 ("livepatch/module: remove livepatch module
notifier") and their surroundings.
So unless there is a reason for the change (which should be then carefully
reviewed and properly tested), I would prefer to keep it as is. What is
the motivation? I am failing to find it in the commit log.
There is no special motivation, i just read btf initialization in module
loading and found direct calls of ftrace and klp, i thought they were
just forgotten to use notifier and i even didn't search git log to
verify, sorry about that.
Honestly, I do think just decoupling ftrace and live kernel patching from
modules is rationale enough, as it makes the code a bit cleaner. But to do
so, we really need to make sure there is absolutely no regressions.
Thus, to allow such a change, I would ask those that are proposing it, show
a full work flow of how ftrace, live kernel patching, and modules work with
each other and why those functions are currently injected in the module code.
As Miroslav stated, we tried to do it via notifiers in the past and it
failed. I don't want to find out why they failed by just adding them back
to notifiers again. Instead, the reasons must be fully understood and
updates made to make sure they will not fail in the future.
Yes, you are right, i read commit msg of 7dcd182bec27, this patch just
reverses it simply and will introduce order issue back. I will try to
find out the problem in the past at first.
Thank you both.
/Song
-- Steve
