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 v13 05/12] livepatch: Refuse to unload only livepatches available during a forced transition
Date: Mon, 15 Oct 2018 14:37:06 +0200 [thread overview]
Message-ID: <20181015123713.25868-6-pmladek@suse.com> (raw)
In-Reply-To: <20181015123713.25868-1-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 make an assumption 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 make some confusion. 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>
---
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 1163742b27c0..77fce7d385df 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -138,6 +138,7 @@ struct klp_object {
* @list: list node for global list of registered patches
* @kobj: kobject for sysfs resources
* @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 {
@@ -149,6 +150,7 @@ struct klp_patch {
struct list_head list;
struct kobject kobj;
bool enabled;
+ bool forced;
struct completion finish;
};
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 17cb974522d0..f38637326ac2 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;
@@ -647,6 +648,7 @@ static int klp_init_patch(struct klp_patch *patch)
mutex_lock(&klp_mutex);
patch->enabled = false;
+ patch->forced = false;
INIT_LIST_HEAD(&patch->list);
init_completion(&patch->finish);
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 982a2e4c6120..30a28634c88c 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:[~2018-10-15 12:37 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-15 12:37 [PATCH v13 00/12] livepatch: Atomic replace feature Petr Mladek
2018-10-15 12:37 ` [PATCH v13 01/12] livepatch: Change void *new_func -> unsigned long new_addr in struct klp_func Petr Mladek
2018-10-15 12:37 ` [PATCH v13 02/12] livepatch: Helper macros to define livepatch structures Petr Mladek
2018-10-17 18:17 ` Josh Poimboeuf
2018-10-18 11:11 ` Petr Mladek
2018-10-18 12:58 ` Josh Poimboeuf
2018-10-24 11:28 ` Petr Mladek
2018-11-21 12:17 ` Miroslav Benes
2018-10-15 12:37 ` [PATCH v13 03/12] livepatch: Shuffle klp_enable_patch()/klp_disable_patch() code Petr Mladek
2018-10-15 12:37 ` [PATCH v13 04/12] livepatch: Consolidate klp_free functions Petr Mladek
2018-10-17 18:22 ` Josh Poimboeuf
2018-10-18 11:40 ` Petr Mladek
2018-11-21 13:59 ` Miroslav Benes
2018-11-21 14:40 ` Petr Mladek
2018-10-15 12:37 ` Petr Mladek [this message]
2018-10-17 18:35 ` [PATCH v13 05/12] livepatch: Refuse to unload only livepatches available during a forced transition Josh Poimboeuf
2018-10-18 12:09 ` Petr Mladek
2018-10-18 13:00 ` Josh Poimboeuf
2018-10-15 12:37 ` [PATCH v13 06/12] livepatch: Simplify API by removing registration step Petr Mladek
2018-10-17 19:06 ` Josh Poimboeuf
2018-10-18 12:33 ` Petr Mladek
2018-10-15 12:37 ` [PATCH v13 07/12] livepatch: Use lists to manage patches, objects and functions Petr Mladek
2018-10-17 20:31 ` Josh Poimboeuf
2018-10-18 12:34 ` Petr Mladek
2018-10-15 12:37 ` [PATCH v13 08/12] livepatch: Add atomic replace Petr Mladek
2018-11-23 12:00 ` Miroslav Benes
2018-10-15 12:37 ` [PATCH v13 09/12] livepatch: Remove Nop structures when unused Petr Mladek
2018-10-17 20:48 ` Josh Poimboeuf
2018-10-18 12:40 ` Petr Mladek
2018-10-15 12:37 ` [PATCH v13 10/12] livepatch: Atomic replace and cumulative patches documentation Petr Mladek
2018-10-15 12:37 ` [PATCH v13 11/12] livepatch: Remove ordering and refuse loading conflicting patches Petr Mladek
2018-10-15 12:37 ` [PATCH v13 12/12] selftests/livepatch: introduce tests Petr Mladek
2018-10-15 19:46 ` Joe Lawrence
2018-10-17 20:48 ` Josh Poimboeuf
2018-10-18 13:34 ` [PATCH v13 00/12] livepatch: Atomic replace feature Josh Poimboeuf
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