From: Miroslav Benes <mbenes@suse.cz>
To: Petr Mladek <pmladek@suse.com>
Cc: Jiri Kosina <jikos@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
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 v15 10/11] livepatch: Remove ordering (stacking) of the livepatches
Date: Thu, 10 Jan 2019 14:56:31 +0100 (CET) [thread overview]
Message-ID: <alpine.LSU.2.21.1901101456150.15065@pobox.suse.cz> (raw)
In-Reply-To: <20190109124329.21991-11-pmladek@suse.com>
On Wed, 9 Jan 2019, Petr Mladek wrote:
> The atomic replace and cumulative patches were introduced as a more secure
> way to handle dependent patches. They simplify the logic:
>
> + Any new cumulative patch is supposed to take over shadow variables
> and changes made by callbacks from previous livepatches.
>
> + All replaced patches are discarded and the modules can be unloaded.
> As a result, there is only one scenario when a cumulative livepatch
> gets disabled.
>
> The different handling of "normal" and cumulative patches might cause
> confusion. It would make sense to keep only one mode. On the other hand,
> it would be rude to enforce using the cumulative livepatches even for
> trivial and independent (hot) fixes.
>
> However, the stack of patches is not really necessary any longer.
> The patch ordering was never clearly visible via the sysfs interface.
> Also the "normal" patches need a lot of caution anyway.
>
> Note that the list of enabled patches is still necessary but the ordering
> is not longer enforced.
>
> Otherwise, the code is ready to disable livepatches in an random order.
> Namely, klp_check_stack_func() always looks for the function from
> the livepatch that is being disabled. klp_func structures are just
> removed from the related func_stack. Finally, the ftrace handlers
> is removed only when the func_stack becomes empty.
>
> Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Miroslav
next prev parent reply other threads:[~2019-01-10 13:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-09 12:43 [PATCH v15 00/11] livepatch: Atomic replace feature Petr Mladek
2019-01-09 12:43 ` [PATCH v15 01/11] livepatch: Change unsigned long old_addr -> void *old_func in struct klp_func Petr Mladek
2019-01-09 12:43 ` [PATCH v15 02/11] livepatch: Shuffle klp_enable_patch()/klp_disable_patch() code Petr Mladek
2019-01-09 12:43 ` [PATCH v15 03/11] livepatch: Consolidate klp_free functions Petr Mladek
2019-01-09 14:35 ` Miroslav Benes
2019-01-09 12:43 ` [PATCH v15 04/11] livepatch: Don't block the removal of patches loaded after a forced transition Petr Mladek
2019-01-09 14:50 ` Miroslav Benes
2019-01-09 12:43 ` [PATCH v15 05/11] livepatch: Simplify API by removing registration step Petr Mladek
2019-01-10 12:32 ` Miroslav Benes
2019-01-09 12:43 ` [PATCH v15 06/11] livepatch: Use lists to manage patches, objects and functions Petr Mladek
2019-01-09 12:43 ` [PATCH v15 07/11] livepatch: Add atomic replace Petr Mladek
2019-01-10 13:05 ` Miroslav Benes
2019-01-09 12:43 ` [PATCH v15 08/11] livepatch: Remove Nop structures when unused Petr Mladek
2019-01-10 13:42 ` Miroslav Benes
2019-01-09 12:43 ` [PATCH v15 09/11] livepatch: Atomic replace and cumulative patches documentation Petr Mladek
2019-01-09 12:43 ` [PATCH v15 10/11] livepatch: Remove ordering (stacking) of the livepatches Petr Mladek
2019-01-10 13:56 ` Miroslav Benes [this message]
2019-01-09 12:43 ` [PATCH v15 11/11] selftests/livepatch: introduce tests Petr Mladek
2019-01-11 17:44 ` [PATCH v15 00/11] livepatch: Atomic replace feature Josh Poimboeuf
2019-01-11 19:56 ` Jiri Kosina
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