debugobjects: extend to assert that an object is initialized

Calling del_timer_sync() on an uninitialized timer leads to a never ending
loop in lock_timer_base() that spins checking for a non-NULL timer base.
Add an assertion to debugobjects to catch usage of uninitialized objects
so that we can initialize timers in the del_timer_sync() path before it
calls lock_timer_base().

[sboyd@codeaurora.org: clarify commit message]
Signed-off-by: Christine Chan <cschan@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/DocBook/debugobjects.tmpl b/Documentation/DocBook/debugobjects.tmpl
index 08ff908aa7a239732fce68cc1b06e507626f216a..24979f691e3e88dd1ab82b3b00633e683445093f 100644 (file)
--- 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 65970b811e22359a7e94afbbf1e0e204ce4ad4dc..0e5f5785d9f2df3c524099142da6202b54f0ff47 100644 (file)
--- 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/lib/debugobjects.c b/lib/debugobjects.c
index 0b07cc5ba23715f5eb2ccc9b15aac56597a8db22..be066faca92d2ba1271292989c05a34e264d506c 100644 (file)
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -569,6 +569,44 @@ out_unlock:
        raw_spin_unlock_irqrestore(&db->lock, flags);
 }
 
+/**
+ * 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