workqueue: Add debugobjects support

Add debugobject support to track the life time of work_structs.

While at it, remove duplicate definition of
INIT_DELAYED_WORK_ON_STACK().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Tejun Heo <tj@kernel.org>

4 files changed, 166 insertions, 15 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 565ebc65920e..ba43dfed353d 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -687,7 +687,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
                 .done   = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
         };
 
-        INIT_WORK(&c_idle.work, do_fork_idle);
+        INIT_WORK_ON_STACK(&c_idle.work, do_fork_idle);
 
         alternatives_smp_switch(1);
 
@@ -713,6 +713,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
 
         if (IS_ERR(c_idle.idle)) {
                 printk("failed fork for CPU %d\n", cpu);
+                destroy_work_on_stack(&c_idle.work);
                 return PTR_ERR(c_idle.idle);
         }
 
@@ -831,6 +832,7 @@ do_rest:
                 smpboot_restore_warm_reset_vector();
         }
 
+        destroy_work_on_stack(&c_idle.work);
         return boot_error;
 }
 
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index cf24c20de9e4..9466e860d8c2 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -25,6 +25,7 @@ typedef void (*work_func_t)(struct work_struct *work);
 struct work_struct {
         atomic_long_t data;
 #define WORK_STRUCT_PENDING 0           /* T if work item pending execution */
+#define WORK_STRUCT_STATIC  1           /* static initializer (debugobjects) */
 #define WORK_STRUCT_FLAG_MASK (3UL)
 #define WORK_STRUCT_WQ_DATA_MASK (~WORK_STRUCT_FLAG_MASK)
         struct list_head entry;
@@ -35,6 +36,7 @@ struct work_struct {
 };
 
 #define WORK_DATA_INIT()        ATOMIC_LONG_INIT(0)
+#define WORK_DATA_STATIC_INIT() ATOMIC_LONG_INIT(2)
 
 struct delayed_work {
         struct work_struct work;
@@ -63,7 +65,7 @@ struct execute_work {
 #endif
 
 #define __WORK_INITIALIZER(n, f) {                              \
-        .data = WORK_DATA_INIT(),                               \
+        .data = WORK_DATA_STATIC_INIT(),                        \
         .entry  = { &(n).entry, &(n).entry },                   \
         .func = (f),                                            \
         __WORK_INIT_LOCKDEP_MAP(#n, &(n))                       \
@@ -91,6 +93,14 @@ struct execute_work {
 #define PREPARE_DELAYED_WORK(_work, _func)                      \
         PREPARE_WORK(&(_work)->work, (_func))
 
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+extern void __init_work(struct work_struct *work, int onstack);
+extern void destroy_work_on_stack(struct work_struct *work);
+#else
+static inline void __init_work(struct work_struct *work, int onstack) { }
+static inline void destroy_work_on_stack(struct work_struct *work) { }
+#endif
+
 /*
  * initialize all of a work item in one go
  *
@@ -99,24 +109,36 @@ struct execute_work {
  * to generate better code.
  */
 #ifdef CONFIG_LOCKDEP
-#define INIT_WORK(_work, _func)                                         \
+#define __INIT_WORK(_work, _func, _onstack)                             \
         do {                                                            \
                 static struct lock_class_key __key;                     \
                                                                         \
+                __init_work((_work), _onstack);                         \
                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
                 lockdep_init_map(&(_work)->lockdep_map, #_work, &__key, 0);\
                 INIT_LIST_HEAD(&(_work)->entry);                        \
                 PREPARE_WORK((_work), (_func));                         \
         } while (0)
 #else
-#define INIT_WORK(_work, _func)                                         \
+#define __INIT_WORK(_work, _func, _onstack)                             \
         do {                                                            \
+                __init_work((_work), _onstack);                         \
                 (_work)->data = (atomic_long_t) WORK_DATA_INIT();       \
                 INIT_LIST_HEAD(&(_work)->entry);                        \
                 PREPARE_WORK((_work), (_func));                         \
         } while (0)
 #endif
 
+#define INIT_WORK(_work, _func)                                 \
+        do {                                                    \
+                __INIT_WORK((_work), (_func), 0);               \
+        } while (0)
+
+#define INIT_WORK_ON_STACK(_work, _func)                        \
+        do {                                                    \
+                __INIT_WORK((_work), (_func), 1);               \
+        } while (0)
+
 #define INIT_DELAYED_WORK(_work, _func)                         \
         do {                                                    \
                 INIT_WORK(&(_work)->work, (_func));             \
@@ -125,22 +147,16 @@ struct execute_work {
 
 #define INIT_DELAYED_WORK_ON_STACK(_work, _func)                \
         do {                                                    \
-                INIT_WORK(&(_work)->work, (_func));             \
+                INIT_WORK_ON_STACK(&(_work)->work, (_func));    \
                 init_timer_on_stack(&(_work)->timer);           \
         } while (0)
 
-#define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)                      \
+#define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)              \
         do {                                                    \
                 INIT_WORK(&(_work)->work, (_func));             \
                 init_timer_deferrable(&(_work)->timer);         \
         } while (0)
 
-#define INIT_DELAYED_WORK_ON_STACK(_work, _func)                \
-        do {                                                    \
-                INIT_WORK(&(_work)->work, (_func));             \
-                init_timer_on_stack(&(_work)->timer);           \
-        } while (0)
-
 /**
  * work_pending - Find out whether a work item is currently pending
  * @work: The work item in question
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 12328147132c..ddad63fbb61b 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -68,6 +68,116 @@ struct workqueue_struct {
 #endif
 };
 
+#ifdef CONFIG_DEBUG_OBJECTS_WORK
+
+static struct debug_obj_descr work_debug_descr;
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int work_fixup_init(void *addr, enum debug_obj_state state)
+{
+        struct work_struct *work = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                cancel_work_sync(work);
+                debug_object_init(work, &work_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ */
+static int work_fixup_activate(void *addr, enum debug_obj_state state)
+{
+        struct work_struct *work = addr;
+
+        switch (state) {
+
+        case ODEBUG_STATE_NOTAVAILABLE:
+                /*
+                 * This is not really a fixup. The work struct was
+                 * statically initialized. We just make sure that it
+                 * is tracked in the object tracker.
+                 */
+                if (test_bit(WORK_STRUCT_STATIC, work_data_bits(work))) {
+                        debug_object_init(work, &work_debug_descr);
+                        debug_object_activate(work, &work_debug_descr);
+                        return 0;
+                }
+                WARN_ON_ONCE(1);
+                return 0;
+
+        case ODEBUG_STATE_ACTIVE:
+                WARN_ON(1);
+
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int work_fixup_free(void *addr, enum debug_obj_state state)
+{
+        struct work_struct *work = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                cancel_work_sync(work);
+                debug_object_free(work, &work_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+static struct debug_obj_descr work_debug_descr = {
+        .name           = "work_struct",
+        .fixup_init     = work_fixup_init,
+        .fixup_activate = work_fixup_activate,
+        .fixup_free     = work_fixup_free,
+};
+
+static inline void debug_work_activate(struct work_struct *work)
+{
+        debug_object_activate(work, &work_debug_descr);
+}
+
+static inline void debug_work_deactivate(struct work_struct *work)
+{
+        debug_object_deactivate(work, &work_debug_descr);
+}
+
+void __init_work(struct work_struct *work, int onstack)
+{
+        if (onstack)
+                debug_object_init_on_stack(work, &work_debug_descr);
+        else
+                debug_object_init(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(__init_work);
+
+void destroy_work_on_stack(struct work_struct *work)
+{
+        debug_object_free(work, &work_debug_descr);
+}
+EXPORT_SYMBOL_GPL(destroy_work_on_stack);
+
+#else
+static inline void debug_work_activate(struct work_struct *work) { }
+static inline void debug_work_deactivate(struct work_struct *work) { }
+#endif
+
 /* Serializes the accesses to the list of workqueues. */
 static DEFINE_SPINLOCK(workqueue_lock);
 static LIST_HEAD(workqueues);
@@ -145,6 +255,7 @@ static void __queue_work(struct cpu_workqueue_struct *cwq,
 {
         unsigned long flags;
 
+        debug_work_activate(work);
         spin_lock_irqsave(&cwq->lock, flags);
         insert_work(cwq, work, &cwq->worklist);
         spin_unlock_irqrestore(&cwq->lock, flags);
@@ -280,6 +391,7 @@ static void run_workqueue(struct cpu_workqueue_struct *cwq)
                 struct lockdep_map lockdep_map = work->lockdep_map;
 #endif
                 trace_workqueue_execution(cwq->thread, work);
+                debug_work_deactivate(work);
                 cwq->current_work = work;
                 list_del_init(cwq->worklist.next);
                 spin_unlock_irq(&cwq->lock);
@@ -350,11 +462,18 @@ static void wq_barrier_func(struct work_struct *work)
 static void insert_wq_barrier(struct cpu_workqueue_struct *cwq,
                         struct wq_barrier *barr, struct list_head *head)
 {
-        INIT_WORK(&barr->work, wq_barrier_func);
+        /*
+         * debugobject calls are safe here even with cwq->lock locked
+         * as we know for sure that this will not trigger any of the
+         * checks and call back into the fixup functions where we
+         * might deadlock.
+         */
+        INIT_WORK_ON_STACK(&barr->work, wq_barrier_func);
         __set_bit(WORK_STRUCT_PENDING, work_data_bits(&barr->work));
 
         init_completion(&barr->done);
 
+        debug_work_activate(&barr->work);
         insert_work(cwq, &barr->work, head);
 }
 
@@ -372,8 +491,10 @@ static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq)
         }
         spin_unlock_irq(&cwq->lock);
 
-        if (active)
+        if (active) {
                 wait_for_completion(&barr.done);
+                destroy_work_on_stack(&barr.work);
+        }
 
         return active;
 }
@@ -451,6 +572,7 @@ out:
                 return 0;
 
         wait_for_completion(&barr.done);
+        destroy_work_on_stack(&barr.work);
         return 1;
 }
 EXPORT_SYMBOL_GPL(flush_work);
@@ -485,6 +607,7 @@ static int try_to_grab_pending(struct work_struct *work)
                  */
                 smp_rmb();
                 if (cwq == get_wq_data(work)) {
+                        debug_work_deactivate(work);
                         list_del_init(&work->entry);
                         ret = 1;
                 }
@@ -507,8 +630,10 @@ static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq,
         }
         spin_unlock_irq(&cwq->lock);
 
-        if (unlikely(running))
+        if (unlikely(running)) {
                 wait_for_completion(&barr.done);
+                destroy_work_on_stack(&barr.work);
+        }
 }
 
 static void wait_on_work(struct work_struct *work)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 234ceb10861f..c91f0519d493 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -298,6 +298,14 @@ config DEBUG_OBJECTS_TIMERS
           timer routines to track the life time of timer objects and
           validate the timer operations.
 
+config DEBUG_OBJECTS_WORK
+        bool "Debug work objects"
+        depends on DEBUG_OBJECTS
+        help
+          If you say Y here, additional code will be inserted into the
+          work queue routines to track the life time of work objects and
+          validate the work operations.
+
 config DEBUG_OBJECTS_ENABLE_DEFAULT
         int "debug_objects bootup default value (0-1)"
         range 0 1