From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
Jason Baron <jbaron@akamai.com>,
Joe Lawrence <joe.lawrence@redhat.com>,
Evgenii Shatokhin <eshatokhin@virtuozzo.com>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v14 05/11] livepatch: Simplify API by removing registration step
Date: Fri, 14 Dec 2018 08:27:10 -0600 [thread overview]
Message-ID: <20181214142710.iprnzxxty5k5vqoz@treble> (raw)
In-Reply-To: <20181214100232.elyqlnjyhp55acxf@pathway.suse.cz>
On Fri, Dec 14, 2018 at 11:02:32AM +0100, Petr Mladek wrote:
> On Thu 2018-12-13 16:46:25, Josh Poimboeuf wrote:
> > Now that we can't re-enable a patch, I wonder if we really need both the
> > 'patch->enabled' and 'klp_target_state' variables?
> >
> > A patch is now always enabled, unless it's in transition, in which case
> > its 'enabled' state is the same as 'klp_target_state'.
> >
> > For example I wonder if we could get rid of 'klp_target_state', since it
> > should be the same as 'klp_transition_patch->enabled'.
>
> There are some catches:
>
> 1. klp_update_patch_state() can be called anywhere and anytime. We
> would add yet another race-sensitive code if we access the flag
> via a pointer.
True.
> 2. patch->enabled is bool while klp_target_state is triple state.
> The argument is that KLP_UNDEFINED helps to catch bugs.
>
>
> > Or alternatively we could get rid of 'patch->enabled', since it should
> > be the same as
> >
> > patch == klp_transition_patch ? klp_target_state : true
>
> This might solve the first catch but not the 2nd one.
It could WARN_ON if it's KLP_UNDEFINED when it's not supposed to be.
> Not to say that it is much harder to read.
We could put it in a klp_patch_enabled(patch) wrapper.
> > Of course this could be a follow-on cleanup patch, which could be done
> > in the future, so as not to hold up the merging of these patches
> > anymore.
>
> Yes, please. This is controversial, non-trivial, and can wait.
No problem.
--
Josh
next prev parent reply other threads:[~2018-12-14 14:27 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-29 9:44 [PATCH v14 00/11] livepatch: Atomic replace feature Petr Mladek
2018-11-29 9:44 ` [PATCH v14 01/11] livepatch: Change unsigned long old_addr -> void *old_func in struct klp_func Petr Mladek
2018-12-03 13:24 ` Miroslav Benes
2018-12-05 18:45 ` Joe Lawrence
2018-12-06 11:08 ` Alice Ferrazzi
2018-11-29 9:44 ` [PATCH v14 02/11] livepatch: Shuffle klp_enable_patch()/klp_disable_patch() code Petr Mladek
2018-12-03 13:36 ` Miroslav Benes
2018-12-05 18:45 ` Joe Lawrence
2018-11-29 9:44 ` [PATCH v14 03/11] livepatch: Consolidate klp_free functions Petr Mladek
2018-12-03 14:59 ` Miroslav Benes
2018-12-04 14:00 ` Petr Mladek
2018-12-13 22:35 ` Josh Poimboeuf
2018-12-14 9:37 ` Miroslav Benes
2018-12-05 19:02 ` Joe Lawrence
2018-12-06 8:15 ` Petr Mladek
2018-12-06 14:23 ` Joe Lawrence
2018-12-13 22:10 ` Josh Poimboeuf
2018-12-14 9:32 ` Petr Mladek
2018-12-14 14:23 ` Josh Poimboeuf
2018-11-29 9:44 ` [PATCH v14 04/11] livepatch: Refuse to unload only livepatches available during a forced transition Petr Mladek
2018-12-03 15:29 ` Miroslav Benes
2018-12-06 8:46 ` Petr Mladek
2018-12-06 9:18 ` Miroslav Benes
2018-12-05 19:05 ` Joe Lawrence
2018-12-13 22:17 ` Josh Poimboeuf
2018-11-29 9:44 ` [PATCH v14 05/11] livepatch: Simplify API by removing registration step Petr Mladek
2018-12-04 12:54 ` Miroslav Benes
2018-12-04 14:47 ` Petr Mladek
2018-12-04 15:32 ` Miroslav Benes
2018-12-05 19:32 ` Joe Lawrence
2018-12-06 8:28 ` Petr Mladek
2018-12-06 9:23 ` Miroslav Benes
2018-12-06 10:14 ` Petr Mladek
2018-12-06 14:36 ` Joe Lawrence
2018-12-13 22:29 ` Josh Poimboeuf
2018-12-14 9:40 ` Petr Mladek
2018-12-14 14:24 ` Josh Poimboeuf
2019-01-03 11:47 ` Petr Mladek
2018-12-13 22:46 ` Josh Poimboeuf
2018-12-14 10:02 ` Petr Mladek
2018-12-14 14:27 ` Josh Poimboeuf [this message]
2018-11-29 9:44 ` [PATCH v14 06/11] livepatch: Use lists to manage patches, objects and functions Petr Mladek
2018-12-04 14:13 ` Miroslav Benes
2018-12-05 19:34 ` Joe Lawrence
2018-11-29 9:44 ` [PATCH v14 07/11] livepatch: Add atomic replace Petr Mladek
2018-12-04 15:27 ` Miroslav Benes
2018-12-05 19:37 ` Joe Lawrence
2018-12-13 22:55 ` Josh Poimboeuf
2018-12-17 15:27 ` Petr Mladek
2019-01-03 12:47 ` Petr Mladek
2019-01-03 13:37 ` Josh Poimboeuf
2018-11-29 9:44 ` [PATCH v14 08/11] livepatch: Remove Nop structures when unused Petr Mladek
2018-12-04 16:08 ` Miroslav Benes
2018-12-05 20:17 ` Joe Lawrence
2018-12-13 23:00 ` Josh Poimboeuf
2018-12-17 15:54 ` Petr Mladek
2018-12-17 16:11 ` Josh Poimboeuf
2018-11-29 9:44 ` [PATCH v14 09/11] livepatch: Atomic replace and cumulative patches documentation Petr Mladek
2018-12-04 16:12 ` Miroslav Benes
2018-12-05 20:20 ` Joe Lawrence
2018-11-29 9:44 ` [PATCH v14 10/11] livepatch: Remove ordering and refuse loading conflicting patches Petr Mladek
2018-12-05 10:27 ` Miroslav Benes
2018-12-05 20:24 ` Joe Lawrence
2018-12-13 23:06 ` Josh Poimboeuf
2018-12-17 16:07 ` Petr Mladek
2018-12-17 16:27 ` Josh Poimboeuf
2018-12-18 8:51 ` Petr Mladek
2018-11-29 9:44 ` [PATCH v14 11/11] selftests/livepatch: introduce tests Petr Mladek
2018-12-05 11:38 ` Miroslav Benes
2018-12-05 20:27 ` Joe Lawrence
2018-12-08 16:54 ` Alice Ferrazzi
2018-12-05 20:49 ` [PATCH v14 00/11] livepatch: Atomic replace feature Joe Lawrence
2018-12-06 7:54 ` Petr Mladek
2018-12-06 9:32 ` Miroslav Benes
2018-12-06 10:15 ` Petr Mladek
2018-12-06 12:37 ` Petr Mladek
2018-12-06 14:29 ` Joe Lawrence
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