linux-stable/kernel/livepatch
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
..
core.c Merge branch 'for-4.16/remove-immediate' into for-linus 2018-01-31 16:36:38 +01:00
core.h Merge branch 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2017-11-15 10:21:58 -08:00
Kconfig livepatch: Make livepatch dependent on !TRIM_UNUSED_KSYMS 2017-05-27 00:27:37 +02:00
Makefile livepatch: introduce shadow variable API 2017-09-14 23:06:12 +02:00
patch.c livepatch: add (un)patch callbacks 2017-10-19 10:08:56 +02:00
patch.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
shadow.c livepatch: Allow to call a custom callback when freeing shadow variables 2018-04-17 13:42:48 +02:00
transition.c livepatch: Remove immediate feature 2018-01-11 10:58:03 +01:00
transition.h livepatch: force transition to finish 2017-12-07 13:21:35 +01:00