Live-Patching Archive on lore.kernel.org
 help / color / Atom feed
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,
	Petr Mladek <pmladek@suse.com>
Subject: [POC 14/23] livepatch: Never block livepatch modules when the related module is being removed
Date: Fri, 17 Jan 2020 16:03:14 +0100
Message-ID: <20200117150323.21801-15-pmladek@suse.com> (raw)
In-Reply-To: <20200117150323.21801-1-pmladek@suse.com>

Originally, it was not possible to remove the single livepatch module when
the code was used during a forced transition. There were no guarantees that
the code was no longer used.

Even the split livepatch modules have to stay when the entire livepatch
gets disabled/replaced and the livepatch modules were used during
a forced transition.

On the other hand, klp_module_going() callback is called when the patched
module is about to be removed. It's code should no longer be used.
The same should be true also for the related livepatch module. Therefore
the livepatch module could always get removed as well.

It allows to load the patched module again in the future. Otherwise,
it would get blocked because the related livepatch module could not
get loaded more times.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 kernel/livepatch/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 73462b66f63f..4b55d805f3ec 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -1391,6 +1391,13 @@ void klp_module_going(struct module *mod)
 	klp_for_each_patch(patch) {
 		klp_for_each_object_safe(patch, obj, tmp_obj) {
 			if (obj->name && !strcmp(obj->name, mod->name)) {
+				/*
+				 * The livepatched module is about to be
+				 * destroyed. It's code is no longer used.
+				 * Same is true for the livepatch even when
+				 * it was part of forced transition.
+				 */
+				obj->forced = false;
 				klp_remove_object(obj);
 			}
 		}
-- 
2.16.4


  parent reply index

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-17 15:03 [POC 00/23] livepatch: Split livepatch module per-object Petr Mladek
2020-01-17 15:03 ` [POC 01/23] module: Allow to delete module also from inside kernel Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-17 15:03 ` [POC 02/23] livepatch: Split livepatch modules per livepatched object Petr Mladek
2020-01-21 11:11   ` Julien Thierry
2020-01-28 12:16     ` Petr Mladek
2020-01-17 15:03 ` [POC 03/23] livepatch: Better checks of struct klp_object definition Petr Mladek
2020-01-21 11:27   ` Julien Thierry
2020-01-17 15:03 ` [POC 04/23] livepatch: Prevent loading livepatch sub-module unintentionally Petr Mladek
2020-01-17 15:03 ` [POC 05/23] livepatch: Initialize and free livepatch submodule Petr Mladek
2020-01-21 11:58   ` Julien Thierry
2020-01-17 15:03 ` [POC 06/23] livepatch: Enable the " Petr Mladek
2020-01-17 15:03 ` [POC 07/23] livepatch: Remove obsolete functionality from klp_module_coming() Petr Mladek
2020-01-17 15:03 ` [POC 08/23] livepatch: Automatically load livepatch module when the patch module is loaded Petr Mladek
2020-01-17 15:03 ` [POC 09/23] livepatch: Handle race when livepatches are reloaded during a module load Petr Mladek
2020-01-22 18:51   ` Julien Thierry
2020-01-17 15:03 ` [POC 10/23] livepatch: Handle modprobe exit code Petr Mladek
2020-01-17 15:03 ` [POC 11/23] livepatch: Safely detect forced transition when removing split livepatch modules Petr Mladek
2020-01-22 10:15   ` Julien Thierry
2020-01-17 15:03 ` [POC 12/23] livepatch: Automatically remove livepatch module when the object is freed Petr Mladek
2020-01-17 15:03 ` [POC 13/23] livepatch: Remove livepatch module when the livepatched module is unloaded Petr Mladek
2020-01-17 15:03 ` Petr Mladek [this message]
2020-01-17 15:03 ` [POC 15/23] livepatch: Prevent infinite loop when loading livepatch module Petr Mladek
2020-01-17 15:03 ` [POC 16/23] livepatch: Add patch into the global list early Petr Mladek
2020-01-17 15:03 ` [POC 17/23] livepatch: Load livepatches for modules when loading the main livepatch Petr Mladek
2020-01-17 15:03 ` [POC 18/23] module: Refactor add_unformed_module() Petr Mladek
2020-01-17 15:03 ` [POC 19/23] module/livepatch: Allow to use exported symbols from livepatch module for "vmlinux" Petr Mladek
2020-01-17 15:03 ` [POC 20/23] module/livepatch: Relocate local variables in the module loaded when the livepatch is being loaded Petr Mladek
2020-01-18 10:29   ` kbuild test robot
2020-01-17 15:03 ` [POC 21/23] livepatch: Remove obsolete arch_klp_init_object_loaded() Petr Mladek
2020-01-17 15:03 ` [POC 22/23] livepatch/module: Remove obsolete copy_module_elf() Petr Mladek
2020-01-17 15:03 ` [POC 23/23] module: Remove obsolete module_disable_ro() Petr Mladek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200117150323.21801-15-pmladek@suse.com \
    --to=pmladek@suse.com \
    --cc=jikos@kernel.org \
    --cc=joe.lawrence@redhat.com \
    --cc=jpoimboe@redhat.com \
    --cc=kamalesh@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=live-patching@vger.kernel.org \
    --cc=mbenes@suse.cz \
    --cc=nstange@suse.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Live-Patching Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/live-patching/0 live-patching/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 live-patching live-patching/ https://lore.kernel.org/live-patching \
		live-patching@vger.kernel.org
	public-inbox-index live-patching

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.live-patching


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git