From: Petr Mladek <pmladek@suse.com>
To: Jiri Kosina <jikos@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Nicolai Stange <nstange@suse.de>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC 3/5] livepatch: Allow to distinguish different version of system state changes
Date: Thu, 18 Jul 2019 11:08:00 +0200 [thread overview]
Message-ID: <20190718090800.gd2neswknsnmey2h@pathway.suse.cz> (raw)
In-Reply-To: <20190611135627.15556-4-pmladek@suse.com>
On Tue 2019-06-11 15:56:25, Petr Mladek wrote:
> It might happen that an older change is not enough and the same system
> state has to be modified another way. Different changes need to get
> distinguished by a version number added to struct klp_state.
>
> The version can also be used to prevent loading incompatible livepatches.
> The check is done when the livepatch is enabled. The rules are:
>
> + Any completely new system state modification is allowed.
>
> + System state modifications with the same or higher version are allowed
> for already modified system states.
>
> + Cumulative livepatches must handle all system state modifications from
> already installed livepatches.
>
> + Non-cumulative livepatches are allowed to touch already modified
> system states.
>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
> ---
> include/linux/livepatch.h | 2 ++
> kernel/livepatch/core.c | 8 ++++++++
> kernel/livepatch/state.c | 40 +++++++++++++++++++++++++++++++++++++++-
> kernel/livepatch/state.h | 9 +++++++++
> 4 files changed, 58 insertions(+), 1 deletion(-)
> create mode 100644 kernel/livepatch/state.h
>
> diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
> index 591abdee30d7..8bc4c6cc3f3f 100644
> --- a/include/linux/livepatch.h
> +++ b/include/linux/livepatch.h
> @@ -135,10 +135,12 @@ struct klp_object {
> /**
> * struct klp_state - state of the system modified by the livepatch
> * @id: system state identifier (non zero)
> + * @version: version of the change (non-zero)
> * @data: custom data
> */
> struct klp_state {
> int id;
As suggested by Nicolay, there will be in v2:
unsigned long id;
> + int version;
It would make sense to make "version" unsigned as well.
I am just unsure about the size:
+ "unsigned long" looks like an overhead to me
+ "u8" might be enough
But I would stay on the safe side and use:
unsigned int version;
Is anyone against?
Best Regards,
Petr
prev parent reply other threads:[~2019-07-18 9:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190611135627.15556-1-pmladek@suse.com>
2019-06-21 13:19 ` [RFC 0/5] livepatch: new API to track system state changes Joe Lawrence
[not found] ` <20190611135627.15556-3-pmladek@suse.com>
2019-06-21 13:43 ` [RFC 2/5] livepatch: Basic " Joe Lawrence
2019-06-24 9:32 ` Nicolai Stange
[not found] ` <20190611135627.15556-5-pmladek@suse.com>
2019-06-21 14:15 ` [RFC 4/5] livepatch: Documentation of the new API for tracking " Joe Lawrence
[not found] ` <20190611135627.15556-6-pmladek@suse.com>
2019-06-21 11:54 ` [RFC 5/5] livepatch: Selftests of the " Miroslav Benes
2019-06-21 14:19 ` Joe Lawrence
2019-06-24 9:27 ` [RFC 0/5] livepatch: new API to track " Nicolai Stange
[not found] ` <20190611135627.15556-4-pmladek@suse.com>
2019-06-21 11:27 ` [RFC 3/5] livepatch: Allow to distinguish different version of " Miroslav Benes
2019-06-21 14:09 ` Joe Lawrence
2019-06-21 15:00 ` Joe Lawrence
2019-06-24 10:26 ` Nicolai Stange
2019-07-18 11:38 ` Petr Mladek
2019-07-18 9:08 ` Petr Mladek [this message]
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