Hi Motomasa,

On Sun, Dec 21, 2025 at 5:09 AM 鈴木幹理 <[email protected]> wrote:
>
> Hi Tao,
>
> Thank you for the review and comments.
>
> > The TRANSITION mark indicating a live patch is activating or
> > deactivating or either? I mean, when people see the TRANSITION flag,
> > do they know the exact operation that is on the system, like it is
> > patching, or unpatching, or it doesn't distinguish the operation at
> > all?
>
> [TRANSITION] now explicitly means “a livepatch transition is in
> progress,” without distinguishing enable vs. disable. The intent is to
> surface that the system is in a transient state.

OK, I see.

>
> > Your above code is 1) check if transition_patch is null. 2) check if
> > transition_patch is within the klp_patches list.
> >
> > But I see in the kernel source, there are only lists to be added into
> > the klp_patches list, no one is to be deleted [1]. So my assumption
> > is, transition_patch will always be found within klp_patches. Because
> > for all livepatches, they must go through klp_enable_patch() ->
> > klp_init_patch() -> list_add_tail(&patch->list, &klp_patches), and no
> > one to be deleted from klp_patches afterwards, so transition_patch
> > must be one of those. If my assumption is correct, is step 2)
> > necessary?
>
> Step 2 is still necessary.
> A patch can be removed from the klp_patches list by
> klp_free_patch_async(), which can be reached via the path:
> enabled_store() -> __klp_disable_patch().
> Although it is unlikely that klp_transition_patch is not in klp_patches,
> this is not guaranteed, so it is safer to keep the additional
> list membership check.

Right, klp_free_patch_async() will free the patch from the klp_patches
list, I didn't notice that, thanks for your explanation!

Thanks,
Tao Liu

>
>
> > And also for the list iteration in step 2), I suggest using the
> > do_list() function of crash utility, you can refer to
> > memory.c:dump_vmap_area() to get an example of do_list() usage.
>
> That's a good idea! I agree with you.
> I wasn’t aware of this helper in the crash utility, so I will update the code
> accordingly and send a v2 patch.
>
>
> Best regards,
> Motomasa Suzuki
>
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