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    Subject[PATCH 05/15] workqueue: set delayed_work->timer function on initialization
    Date
    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>
    ---
    include/linux/workqueue.h | 13 +++++++++++--
    kernel/workqueue.c | 7 ++++---
    2 files changed, 15 insertions(+), 5 deletions(-)

    diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
    index 278dc5d..ab95fef 100644
    --- 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 147869a..db8098b 100644
    --- a/kernel/workqueue.c
    +++ b/kernel/workqueue.c
    @@ -1112,13 +1112,14 @@ 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);

    __queue_work(smp_processor_id(), cwq->wq, &dwork->work);
    }
    +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);
    --
    1.7.7.3


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