From: Petr Mladek <pmladek@suse.com>
To: Jiri Kosina <jikos@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Miroslav Benes <mbenes@suse.cz>
Cc: 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,
Petr Mladek <pmladek@suse.com>
Subject: [PATCH v15 04/11] livepatch: Don't block the removal of patches loaded after a forced transition
Date: Wed, 9 Jan 2019 13:43:22 +0100 [thread overview]
Message-ID: <20190109124329.21991-5-pmladek@suse.com> (raw)
In-Reply-To: <20190109124329.21991-1-pmladek@suse.com>
module_put() is currently never called in klp_complete_transition() when
klp_force is set. As a result, we might keep the reference count even when
klp_enable_patch() fails and klp_cancel_transition() is called.
This might give the impression that a module might get blocked in some
strange init state. Fortunately, it is not the case. The reference count
is ignored when mod->init fails and erroneous modules are always removed.
Anyway, this might be confusing. Instead, this patch moves
the global klp_forced flag into struct klp_patch. As a result,
we block only modules that might still be in use after a forced
transition. Newly loaded livepatches might be eventually completely
removed later.
It is not a big deal. But the code is at least consistent with
the reality.
Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
---
include/linux/livepatch.h | 2 ++
kernel/livepatch/core.c | 4 +++-
kernel/livepatch/core.h | 1 +
kernel/livepatch/transition.c | 10 +++++-----
4 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 6978785bc059..6a9165d9b090 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -143,6 +143,7 @@ struct klp_object {
* @kobj: kobject for sysfs resources
* @kobj_added: @kobj has been added and needs freeing
* @enabled: the patch is enabled (but operation may be incomplete)
+ * @forced: was involved in a forced transition
* @finish: for waiting till it is safe to remove the patch module
*/
struct klp_patch {
@@ -155,6 +156,7 @@ struct klp_patch {
struct kobject kobj;
bool kobj_added;
bool enabled;
+ bool forced;
struct completion finish;
};
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 6f0d9095f662..e77c5017ae0c 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -45,7 +45,8 @@
*/
DEFINE_MUTEX(klp_mutex);
-static LIST_HEAD(klp_patches);
+/* Registered patches */
+LIST_HEAD(klp_patches);
static struct kobject *klp_root_kobj;
@@ -659,6 +660,7 @@ static int klp_init_patch_early(struct klp_patch *patch)
INIT_LIST_HEAD(&patch->list);
patch->kobj_added = false;
patch->enabled = false;
+ patch->forced = false;
init_completion(&patch->finish);
klp_for_each_object(patch, obj) {
diff --git a/kernel/livepatch/core.h b/kernel/livepatch/core.h
index 48a83d4364cf..d0cb5390e247 100644
--- a/kernel/livepatch/core.h
+++ b/kernel/livepatch/core.h
@@ -5,6 +5,7 @@
#include <linux/livepatch.h>
extern struct mutex klp_mutex;
+extern struct list_head klp_patches;
static inline bool klp_is_object_loaded(struct klp_object *obj)
{
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index f27a378ad5e1..a4c921364003 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -33,8 +33,6 @@ struct klp_patch *klp_transition_patch;
static int klp_target_state = KLP_UNDEFINED;
-static bool klp_forced = false;
-
/*
* This work can be performed periodically to finish patching or unpatching any
* "straggler" tasks which failed to transition in the first attempt.
@@ -137,10 +135,10 @@ static void klp_complete_transition(void)
klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
/*
- * klp_forced set implies unbounded increase of module's ref count if
+ * patch->forced set implies unbounded increase of module's ref count if
* the module is disabled/enabled in a loop.
*/
- if (!klp_forced && klp_target_state == KLP_UNPATCHED)
+ if (!klp_transition_patch->forced && klp_target_state == KLP_UNPATCHED)
module_put(klp_transition_patch->mod);
klp_target_state = KLP_UNDEFINED;
@@ -620,6 +618,7 @@ void klp_send_signals(void)
*/
void klp_force_transition(void)
{
+ struct klp_patch *patch;
struct task_struct *g, *task;
unsigned int cpu;
@@ -633,5 +632,6 @@ void klp_force_transition(void)
for_each_possible_cpu(cpu)
klp_update_patch_state(idle_task(cpu));
- klp_forced = true;
+ list_for_each_entry(patch, &klp_patches, list)
+ patch->forced = true;
}
--
2.13.7
next prev parent reply other threads:[~2019-01-09 12:44 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 ` Petr Mladek [this message]
2019-01-09 14:50 ` [PATCH v15 04/11] livepatch: Don't block the removal of patches loaded after a forced transition 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
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
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=20190109124329.21991-5-pmladek@suse.com \
--to=pmladek@suse.com \
--cc=eshatokhin@virtuozzo.com \
--cc=jbaron@akamai.com \
--cc=jikos@kernel.org \
--cc=joe.lawrence@redhat.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=mbenes@suse.cz \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).