Merge branch 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

* 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timer: Use debugobjects to catch deletion of uninitialized timers
  timer: Setup uninitialized timer with a stub callback
  debugobjects: Extend to assert that an object is initialized
  debugobjects: Be smarter about static objects

4 files changed, 162 insertions, 10 deletions

diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl
index 08ff908aa7a2..24979f691e3e 100644
--- a/Documentation/DocBook/debugobjects.tmpl
+++ b/Documentation/DocBook/debugobjects.tmpl
@@ -96,6 +96,7 @@
         <listitem><para>debug_object_deactivate</para></listitem>
         <listitem><para>debug_object_destroy</para></listitem>
         <listitem><para>debug_object_free</para></listitem>
+        <listitem><para>debug_object_assert_init</para></listitem>
       </itemizedlist>
       Each of these functions takes the address of the real object and
       a pointer to the object type specific debug description
@@ -273,6 +274,26 @@
         debug checks.
       </para>
     </sect1>
+
+    <sect1 id="debug_object_assert_init">
+      <title>debug_object_assert_init</title>
+      <para>
+        This function is called to assert that an object has been
+        initialized.
+      </para>
+      <para>
+        When the real object is not tracked by debugobjects, it calls
+        fixup_assert_init of the object type description structure
+        provided by the caller, with the hardcoded object state
+        ODEBUG_NOT_AVAILABLE. The fixup function can correct the problem
+        by calling debug_object_init and other specific initializing
+        functions.
+      </para>
+      <para>
+        When the real object is already tracked by debugobjects it is
+        ignored.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="fixupfunctions">
     <title>Fixup functions</title>
@@ -381,6 +402,35 @@
         statistics.
       </para>
     </sect1>
+    <sect1 id="fixup_assert_init">
+      <title>fixup_assert_init</title>
+      <para>
+        This function is called from the debug code whenever a problem
+        in debug_object_assert_init is detected.
+      </para>
+      <para>
+        Called from debug_object_assert_init() with a hardcoded state
+        ODEBUG_STATE_NOTAVAILABLE when the object is not found in the
+        debug bucket.
+      </para>
+      <para>
+        The function returns 1 when the fixup was successful,
+        otherwise 0. The return value is used to update the
+        statistics.
+      </para>
+      <para>
+        Note, this function should make sure debug_object_init() is
+        called before returning.
+      </para>
+      <para>
+        The handling of statically initialized objects is a special
+        case. The fixup function should check if this is a legitimate
+        case of a statically initialized object or not. In this case only
+        debug_object_init() should be called to make the object known to
+        the tracker. Then the function should return 0 because this is not
+        a real fixup.
+      </para>
+    </sect1>
   </chapter>
   <chapter id="bugs">
     <title>Known Bugs And Assumptions</title>
diff --git a/include/linux/debugobjects.h b/include/linux/debugobjects.h
index 65970b811e22..0e5f5785d9f2 100644
--- a/include/linux/debugobjects.h
+++ b/include/linux/debugobjects.h
@@ -46,6 +46,8 @@ struct debug_obj {
  *                      fails
  * @fixup_free:         fixup function, which is called when the free check
  *                      fails
+ * @fixup_assert_init:  fixup function, which is called when the assert_init
+ *                      check fails
  */
 struct debug_obj_descr {
         const char              *name;
@@ -54,6 +56,7 @@ struct debug_obj_descr {
         int (*fixup_activate)   (void *addr, enum debug_obj_state state);
         int (*fixup_destroy)    (void *addr, enum debug_obj_state state);
         int (*fixup_free)       (void *addr, enum debug_obj_state state);
+        int (*fixup_assert_init)(void *addr, enum debug_obj_state state);
 };
 
 #ifdef CONFIG_DEBUG_OBJECTS
@@ -64,6 +67,7 @@ extern void debug_object_activate  (void *addr, struct debug_obj_descr *descr);
 extern void debug_object_deactivate(void *addr, struct debug_obj_descr *descr);
 extern void debug_object_destroy   (void *addr, struct debug_obj_descr *descr);
 extern void debug_object_free      (void *addr, struct debug_obj_descr *descr);
+extern void debug_object_assert_init(void *addr, struct debug_obj_descr *descr);
 
 /*
  * Active state:
@@ -89,6 +93,8 @@ static inline void
 debug_object_destroy   (void *addr, struct debug_obj_descr *descr) { }
 static inline void
 debug_object_free      (void *addr, struct debug_obj_descr *descr) { }
+static inline void
+debug_object_assert_init(void *addr, struct debug_obj_descr *descr) { }
 
 static inline void debug_objects_early_init(void) { }
 static inline void debug_objects_mem_init(void) { }
diff --git a/kernel/timer.c b/kernel/timer.c
index 9c3c62b0c4bc..a297ffcf888e 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -427,6 +427,12 @@ static int timer_fixup_init(void *addr, enum debug_obj_state state)
         }
 }
 
+/* Stub timer callback for improperly used timers. */
+static void stub_timer(unsigned long data)
+{
+        WARN_ON(1);
+}
+
 /*
  * fixup_activate is called when:
  * - an active object is activated
@@ -450,7 +456,8 @@ static int timer_fixup_activate(void *addr, enum debug_obj_state state)
                         debug_object_activate(timer, &timer_debug_descr);
                         return 0;
                 } else {
-                        WARN_ON_ONCE(1);
+                        setup_timer(timer, stub_timer, 0);
+                        return 1;
                 }
                 return 0;
 
@@ -480,12 +487,40 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state)
         }
 }
 
+/*
+ * fixup_assert_init is called when:
+ * - an untracked/uninit-ed object is found
+ */
+static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
+{
+        struct timer_list *timer = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_NOTAVAILABLE:
+                if (timer->entry.prev == TIMER_ENTRY_STATIC) {
+                        /*
+                         * This is not really a fixup. The timer was
+                         * statically initialized. We just make sure that it
+                         * is tracked in the object tracker.
+                         */
+                        debug_object_init(timer, &timer_debug_descr);
+                        return 0;
+                } else {
+                        setup_timer(timer, stub_timer, 0);
+                        return 1;
+                }
+        default:
+                return 0;
+        }
+}
+
 static struct debug_obj_descr timer_debug_descr = {
-        .name           = "timer_list",
-        .debug_hint     = timer_debug_hint,
-        .fixup_init     = timer_fixup_init,
-        .fixup_activate = timer_fixup_activate,
-        .fixup_free     = timer_fixup_free,
+        .name                   = "timer_list",
+        .debug_hint             = timer_debug_hint,
+        .fixup_init             = timer_fixup_init,
+        .fixup_activate         = timer_fixup_activate,
+        .fixup_free             = timer_fixup_free,
+        .fixup_assert_init      = timer_fixup_assert_init,
 };
 
 static inline void debug_timer_init(struct timer_list *timer)
@@ -508,6 +543,11 @@ static inline void debug_timer_free(struct timer_list *timer)
         debug_object_free(timer, &timer_debug_descr);
 }
 
+static inline void debug_timer_assert_init(struct timer_list *timer)
+{
+        debug_object_assert_init(timer, &timer_debug_descr);
+}
+
 static void __init_timer(struct timer_list *timer,
                          const char *name,
                          struct lock_class_key *key);
@@ -531,6 +571,7 @@ EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
 static inline void debug_timer_init(struct timer_list *timer) { }
 static inline void debug_timer_activate(struct timer_list *timer) { }
 static inline void debug_timer_deactivate(struct timer_list *timer) { }
+static inline void debug_timer_assert_init(struct timer_list *timer) { }
 #endif
 
 static inline void debug_init(struct timer_list *timer)
@@ -552,6 +593,11 @@ static inline void debug_deactivate(struct timer_list *timer)
         trace_timer_cancel(timer);
 }
 
+static inline void debug_assert_init(struct timer_list *timer)
+{
+        debug_timer_assert_init(timer);
+}
+
 static void __init_timer(struct timer_list *timer,
                          const char *name,
                          struct lock_class_key *key)
@@ -902,6 +948,8 @@ int del_timer(struct timer_list *timer)
         unsigned long flags;
         int ret = 0;
 
+        debug_assert_init(timer);
+
         timer_stats_timer_clear_start_info(timer);
         if (timer_pending(timer)) {
                 base = lock_timer_base(timer, &flags);
@@ -932,6 +980,8 @@ int try_to_del_timer_sync(struct timer_list *timer)
         unsigned long flags;
         int ret = -1;
 
+        debug_assert_init(timer);
+
         base = lock_timer_base(timer, &flags);
 
         if (base->running_timer == timer)
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index a78b7c6e042c..77cb245f8e7b 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -268,12 +268,16 @@ static void debug_print_object(struct debug_obj *obj, char *msg)
  * Try to repair the damage, so we have a better chance to get useful
  * debug output.
  */
-static void
+static int
 debug_object_fixup(int (*fixup)(void *addr, enum debug_obj_state state),
                    void * addr, enum debug_obj_state state)
 {
+        int fixed = 0;
+
         if (fixup)
-                debug_objects_fixups += fixup(addr, state);
+                fixed = fixup(addr, state);
+        debug_objects_fixups += fixed;
+        return fixed;
 }
 
 static void debug_object_is_on_stack(void *addr, int onstack)
@@ -386,6 +390,9 @@ void debug_object_activate(void *addr, struct debug_obj_descr *descr)
         struct debug_bucket *db;
         struct debug_obj *obj;
         unsigned long flags;
+        struct debug_obj o = { .object = addr,
+                               .state = ODEBUG_STATE_NOTAVAILABLE,
+                               .descr = descr };
 
         if (!debug_objects_enabled)
                 return;
@@ -425,8 +432,9 @@ void debug_object_activate(void *addr, struct debug_obj_descr *descr)
          * let the type specific code decide whether this is
          * true or not.
          */
-        debug_object_fixup(descr->fixup_activate, addr,
-                           ODEBUG_STATE_NOTAVAILABLE);
+        if (debug_object_fixup(descr->fixup_activate, addr,
+                           ODEBUG_STATE_NOTAVAILABLE))
+                debug_print_object(&o, "activate");
 }
 
 /**
@@ -563,6 +571,44 @@ out_unlock:
 }
 
 /**
+ * debug_object_assert_init - debug checks when object should be init-ed
+ * @addr:       address of the object
+ * @descr:      pointer to an object specific debug description structure
+ */
+void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)
+{
+        struct debug_bucket *db;
+        struct debug_obj *obj;
+        unsigned long flags;
+
+        if (!debug_objects_enabled)
+                return;
+
+        db = get_bucket((unsigned long) addr);
+
+        raw_spin_lock_irqsave(&db->lock, flags);
+
+        obj = lookup_object(addr, db);
+        if (!obj) {
+                struct debug_obj o = { .object = addr,
+                                       .state = ODEBUG_STATE_NOTAVAILABLE,
+                                       .descr = descr };
+
+                raw_spin_unlock_irqrestore(&db->lock, flags);
+                /*
+                 * Maybe the object is static.  Let the type specific
+                 * code decide what to do.
+                 */
+                if (debug_object_fixup(descr->fixup_assert_init, addr,
+                                       ODEBUG_STATE_NOTAVAILABLE))
+                        debug_print_object(&o, "assert_init");
+                return;
+        }
+
+        raw_spin_unlock_irqrestore(&db->lock, flags);
+}
+
+/**
  * debug_object_active_state - debug checks object usage state machine
  * @addr:       address of the object
  * @descr:      pointer to an object specific debug description structure