linux-kernel - Re: [PATCH] livepatch: fix merge bug in klp_cleanup_module_patches

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Date:   Tue, 31 Oct 2017 21:12:07 +0100 (CET)
From:   Jiri Kosina <jikos@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
cc:     Miroslav Benes <mbenes@...e.cz>, Jessica Yu <jeyu@...hat.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        Joe Lawrence <joe.lawrence@...hat.com>
Subject: Re: [PATCH] livepatch: fix merge bug in
 klp_cleanup_module_patches_limited()

On Tue, 31 Oct 2017, Josh Poimboeuf wrote:

> When the patch for "livepatch: add (un)patch callbacks" was posted to
> the mailing list at:
> 
>   https://lkml.kernel.org/r/1507921723-1996-2-git-send-email-joe.lawrence@redhat.com
> 
> ... it was based on top of the following commit:
> 
>   ef8daf8eeb5b ("livepatch: unpatch all klp_objects if klp_module_coming fails").
> 
> But when it was applied to git on the livepatching
> for-4.15/shadow-variables branch, that branch was missing the above
> commit.  The patch was rebased accordingly:
> 
>   93862e385ded ("livepatch: add (un)patch callbacks")
> 
> Then the two above commits were merged into livepatching/for-next:
> 
>   6a18fdf2d8d3 ("Merge branch 'for-4.15/callbacks' into for-next"),
> 
> The result of the merge commit was that the klp_post_unpatch_callback()
> call in the klp_cleanup_module_patches_limited() function disappeared.
> The original patch on the mailing list had that call, so put it back.
> 
> Fixes: 6a18fdf2d8d3 ("Merge branch 'for-4.15/callbacks' into for-next")
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> ---
>  kernel/livepatch/core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
> index 30e392858281..de9e45dca70f 100644
> --- a/kernel/livepatch/core.c
> +++ b/kernel/livepatch/core.c
> @@ -875,6 +875,8 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
>  				pr_notice("reverting patch '%s' on unloading module '%s'\n",
>  					  patch->mod->name, obj->mod->name);
>  				klp_unpatch_object(obj);
> +
> +				klp_post_unpatch_callback(obj);

Bah, thanks a lot for spotting and fixing my brainfart, really 
appreciated.

Now, the only branch I could actually technically apply this patch to 
would be for-next, but that'd be useless, as that is only an 
integration/testing branch, that doesn't get merged anywhere else than 
linux-next.

Would you be okay with me just redoing the merge into for-next with this 
fixup attributed to you in the merge message (and my git-rerere picking it 
up for upstream)?

Thanks Josh,

-- 
Jiri Kosina
SUSE Labs