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Petr Mladek 3b2c77d000 livepatch: Allow to call a custom callback when freeing shadow variables
We might need to do some actions before the shadow variable is freed.
For example, we might need to remove it from a list or free some data
that it points to.

This is already possible now. The user can get the shadow variable
by klp_shadow_get(), do the necessary actions, and then call
klp_shadow_free().

This patch allows to do it a more elegant way. The user could implement
the needed actions in a callback that is passed to klp_shadow_free()
as a parameter. The callback usually does reverse operations to
the constructor callback that can be called by klp_shadow_*alloc().

It is especially useful for klp_shadow_free_all(). There we need to do
these extra actions for each found shadow variable with the given ID.

Note that the memory used by the shadow variable itself is still released
later by rcu callback. It is needed to protect internal structures that
keep all shadow variables. But the destructor is called immediately.
The shadow variable must not be access anyway after klp_shadow_free()
is called. The user is responsible to protect this any suitable way.

Be aware that the destructor is called under klp_shadow_lock. It is
the same as for the contructor in klp_shadow_alloc().

Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2018-04-17 13:42:48 +02:00
arch Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2018-01-31 13:02:18 -08:00
block Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
Documentation livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
drivers Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2018-01-31 13:00:01 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs New in this version: 2018-01-31 10:18:00 -08:00
include livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
init init_task out-of-lining 2018-01-29 09:08:34 -08:00
ipc Merge branch 'work.mqueue' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 18:32:21 -08:00
kernel livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
lib First merge window pull request for 4.16 2018-01-31 12:05:10 -08:00
mm Merge branch 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 10:01:08 -08:00
net Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid 2018-01-31 13:00:01 -08:00
samples livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
scripts Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-30 10:15:30 -08:00
security Merge branch 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-30 17:58:07 -08:00
sound Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 09:25:20 -08:00
tools The is the bulk of GPIO changes for the v4.16 kernel cycle. 2018-01-31 12:25:27 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Merge branch 'work.get_user_pages_fast' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-01-31 10:01:08 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS power supply and reset changes for the v4.16 series 2018-01-31 12:55:31 -08:00
Makefile Linux 4.15 2018-01-28 13:20:33 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.