debugobjects: Add hint for better object identification

In complex subsystems like mac80211 structures can contain several
timers and work structs, so identifying a specific instance from the
call trace and object type output of debugobjects can be hard.

Allow the subsystems which support debugobjects to provide a hint
function. This function returns a pointer to a kernel address
(preferrably the objects callback function) which is printed along
with the debugobjects type.

Add hint methods for timer_list, work_struct and hrtimer.

[ tglx: Massaged changelog, made it compile ]

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
LKML-Reference: <20110307085809.GA9334@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

5 files changed, 28 insertions, 4 deletions

diff --git a/include/linux/debugobjects.h b/include/linux/debugobjects.h
index 597692f1fc8d..65970b811e22 100644
--- a/include/linux/debugobjects.h
+++ b/include/linux/debugobjects.h
@@ -34,7 +34,10 @@ struct debug_obj {
 
 /**
  * struct debug_obj_descr - object type specific debug description structure
+ *
  * @name:               name of the object typee
+ * @debug_hint:         function returning address, which have associated
+ *                      kernel symbol, to allow identify the object
  * @fixup_init:         fixup function, which is called when the init check
  *                      fails
  * @fixup_activate:     fixup function, which is called when the activate check
@@ -46,7 +49,7 @@ struct debug_obj {
  */
 struct debug_obj_descr {
         const char              *name;
-
+        void *(*debug_hint)     (void *addr);
         int (*fixup_init)       (void *addr, enum debug_obj_state state);
         int (*fixup_activate)   (void *addr, enum debug_obj_state state);
         int (*fixup_destroy)    (void *addr, enum debug_obj_state state);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 0c8d7c048615..e38f5a073d01 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -334,6 +334,11 @@ EXPORT_SYMBOL_GPL(ktime_add_safe);
 
 static struct debug_obj_descr hrtimer_debug_descr;
 
+static void *hrtimer_debug_hint(void *addr)
+{
+        return ((struct hrtimer *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized
@@ -393,6 +398,7 @@ static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr hrtimer_debug_descr = {
         .name           = "hrtimer",
+        .debug_hint     = hrtimer_debug_hint,
         .fixup_init     = hrtimer_fixup_init,
         .fixup_activate = hrtimer_fixup_activate,
         .fixup_free     = hrtimer_fixup_free,
diff --git a/kernel/timer.c b/kernel/timer.c
index d6459923d245..33a67925d900 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -404,6 +404,11 @@ static void timer_stats_account_timer(struct timer_list *timer) {}
 
 static struct debug_obj_descr timer_debug_descr;
 
+static void *timer_debug_hint(void *addr)
+{
+        return ((struct timer_list *) addr)->function;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized
@@ -477,6 +482,7 @@ static int timer_fixup_free(void *addr, enum debug_obj_state state)
 
 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,
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index ee6578b578ad..b5fe4c00eb3c 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -316,6 +316,11 @@ static inline int __next_wq_cpu(int cpu, const struct cpumask *mask,
 
 static struct debug_obj_descr work_debug_descr;
 
+static void *work_debug_hint(void *addr)
+{
+        return ((struct work_struct *) addr)->func;
+}
+
 /*
  * fixup_init is called when:
  * - an active object is initialized
@@ -387,6 +392,7 @@ static int work_fixup_free(void *addr, enum debug_obj_state state)
 
 static struct debug_obj_descr work_debug_descr = {
         .name           = "work_struct",
+        .debug_hint     = work_debug_hint,
         .fixup_init     = work_fixup_init,
         .fixup_activate = work_fixup_activate,
         .fixup_free     = work_fixup_free,
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index deebcc57d4e6..9d86e45086f5 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -249,14 +249,17 @@ static struct debug_bucket *get_bucket(unsigned long addr)
 
 static void debug_print_object(struct debug_obj *obj, char *msg)
 {
+        struct debug_obj_descr *descr = obj->descr;
         static int limit;
 
-        if (limit < 5 && obj->descr != descr_test) {
+        if (limit < 5 && descr != descr_test) {
+                void *hint = descr->debug_hint ?
+                        descr->debug_hint(obj->object) : NULL;
                 limit++;
                 WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
-                                 "object type: %s\n",
+                                 "object type: %s hint: %pS\n",
                         msg, obj_states[obj->state], obj->astate,
-                        obj->descr->name);
+                        descr->name, hint);
         }
         debug_objects_warnings++;
 }