Messages in this thread | | | From | richard clark <> | Date | Mon, 5 Dec 2022 14:18:35 +0800 | Subject | work item still be scheduled to execute after destroy_workqueue? |
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Hi Lai and Tejun,
Why can the work still be queued to and executed when queueing it to a wq has been destroyed, for instance, the below code snippet in a kernel module: ---------------------->8---------------------
struct workqueue_struct *wq0; #define MAX_ACTIVE_WORKS (3)
static void work0_func(struct work_struct *work); static void work1_func(struct work_struct *work); static void work2_func(struct work_struct *work);
static DECLARE_WORK(w0, work0_func); static DECLARE_WORK(w1, work1_func); static DECLARE_WORK(w2, work2_func);
/* work->func */ static void work0_func(struct work_struct *work) { pr_info("+%s begins to sleep\n", __func__); /* sleep for 10s */ schedule_timeout_interruptible(msecs_to_jiffies(10000)); pr_info("+%s after sleep, begin to queue another work\n", __func__); queue_work_on(1, wq0, &w1); }
/* work->func */ static void work1_func(struct work_struct *work) { pr_info("+%s scheduled\n", __func__); }
/* work->func */ static void work2_func(struct work_struct *work) { pr_info("+%s scheduled\n", __func__); }
static int destroy_init(void) { wq0 = alloc_workqueue("percpu_wq0", 0, MAX_ACTIVE_WORKS); if (!wq0) { pr_err("alloc_workqueue failed\n"); return -1; } queue_work_on(1, wq0, &w0); pr_info("Begin to destroy wq0...\n"); destroy_workqueue(wq0); pr_info("queue w2 to the wq0 after destroyed...\n"); queue_work_on(1, wq0, &w2);
return 0; }
The output on my x86_64 box is:
[344702.734480] +destroy_init+ [344702.734499] Begin to destroy wq0... [344702.734516] +work0_func begins to sleep [344712.791607] +work0_func after sleep, begin to queue another work [344712.791620] +work1_func scheduled [344712.791649] queue w2 to the wq0 after destroyed... [344712.791663] +work2_func scheduled <------------- work 2 still be scheduled?
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