workqueue: set delayed_work->timer function on initialization

delayed_work->timer.function is currently initialized during
queue_delayed_work_on().  Export delayed_work_timer_fn() and set
delayed_work timer function during delayed_work initialization
together with other fields.

This ensures the timer function is always valid on an initialized
delayed_work.  This is to help mod_delayed_work() implementation.

To detect delayed_work users which diddle with the internal timer,
trigger WARN if timer function doesn't match on queue.

Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 278dc5ddb73f1adcb6e41cf612ba6efb3e0d3c89..ab95fef38d5684d33fa9b56fcd70384c3dce0d79 100644 (file)
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -16,6 +16,7 @@ struct workqueue_struct;
 
 struct work_struct;
 typedef void (*work_func_t)(struct work_struct *work);
+void delayed_work_timer_fn(unsigned long __data);
 
 /*
  * The first word is the work queue pointer and the flags rolled into
@@ -124,12 +125,14 @@ struct execute_work {
 
 #define __DELAYED_WORK_INITIALIZER(n, f) {                     \
        .work = __WORK_INITIALIZER((n).work, (f)),              \
-       .timer = TIMER_INITIALIZER(NULL, 0, 0),                 \
+       .timer = TIMER_INITIALIZER(delayed_work_timer_fn,       \
+                               0, (unsigned long)&(n)),        \
        }
 
 #define __DEFERRED_WORK_INITIALIZER(n, f) {                    \
        .work = __WORK_INITIALIZER((n).work, (f)),              \
-       .timer = TIMER_DEFERRED_INITIALIZER(NULL, 0, 0),        \
+       .timer = TIMER_DEFERRED_INITIALIZER(delayed_work_timer_fn, \
+                               0, (unsigned long)&(n)),        \
        }
 
 #define DECLARE_WORK(n, f)                                     \
@@ -207,18 +210,24 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
        do {                                                    \
                INIT_WORK(&(_work)->work, (_func));             \
                init_timer(&(_work)->timer);                    \
+               (_work)->timer.function = delayed_work_timer_fn;\
+               (_work)->timer.data = (unsigned long)(_work);   \
        } while (0)
 
 #define INIT_DELAYED_WORK_ONSTACK(_work, _func)                        \
        do {                                                    \
                INIT_WORK_ONSTACK(&(_work)->work, (_func));     \
                init_timer_on_stack(&(_work)->timer);           \
+               (_work)->timer.function = delayed_work_timer_fn;\
+               (_work)->timer.data = (unsigned long)(_work);   \
        } while (0)
 
 #define INIT_DELAYED_WORK_DEFERRABLE(_work, _func)             \
        do {                                                    \
                INIT_WORK(&(_work)->work, (_func));             \
                init_timer_deferrable(&(_work)->timer);         \
+               (_work)->timer.function = delayed_work_timer_fn;\
+               (_work)->timer.data = (unsigned long)(_work);   \
        } while (0)
 
 /**

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 30474c4e107c39f3e394cf1f4abc1daa537aa823..55392385fe3083406d8cb8d064d62d251fd27dd3 100644 (file)
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1112,7 +1112,7 @@ bool queue_work(struct workqueue_struct *wq, struct work_struct *work)
 }
 EXPORT_SYMBOL_GPL(queue_work);
 
-static void delayed_work_timer_fn(unsigned long __data)
+void delayed_work_timer_fn(unsigned long __data)
 {
        struct delayed_work *dwork = (struct delayed_work *)__data;
        struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work);
@@ -1121,6 +1121,7 @@ static void delayed_work_timer_fn(unsigned long __data)
        __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
        local_irq_enable();
 }
+EXPORT_SYMBOL_GPL(delayed_work_timer_fn);
 
 /**
  * queue_delayed_work_on - queue work on specific CPU after delay
@@ -1145,6 +1146,8 @@ bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
        if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
                unsigned int lcpu;
 
+               WARN_ON_ONCE(timer->function != delayed_work_timer_fn ||
+                            timer->data != (unsigned long)dwork);
                BUG_ON(timer_pending(timer));
                BUG_ON(!list_empty(&work->entry));
 
@@ -1168,8 +1171,6 @@ bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
                set_work_cwq(work, get_cwq(lcpu, wq), 0);
 
                timer->expires = jiffies + delay;
-               timer->data = (unsigned long)dwork;
-               timer->function = delayed_work_timer_fn;
 
                if (unlikely(cpu >= 0))
                        add_timer_on(timer, cpu);