The show_pwq() function dumps out a pool_workqueue structure's activity, including the pending work-queue handlers: Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x1 nice=0 active=10/256 refcnt=11 in-flight: 7:test_work_func, 64:test_work_func, 249:test_work_func pending: test_work_func, test_work_func, test_work_func1, test_work_func1, test_work_func1, test_work_func1, test_work_func1 When large systems are facing certain types of hang conditions, it is not unusual for this "pending" list to contain runs of hundreds of identical function names. This "wall of text" is difficult to read, and worse yet, it can be interleaved with other output such as stack traces. Therefore, make show_pwq() use run-length encoding so that the above printout instead looks like this: Showing busy workqueues and worker pools: workqueue events: flags=0x0 pwq 0: cpus=0 node=0 flags=0x1 nice=0 active=10/256 refcnt=11 in-flight: 7:test_work_func, 64:test_work_func, 249:test_work_func pending: 2*test_work_func, 5*test_work_func1 When no comma would be printed, including the WORK_STRUCT_LINKED case, a new run is started unconditionally. This output is more readable, places less stress on the hardware, firmware, and software on the console-log path, and reduces interference with other output.
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| @@ -4718,22 +4718,53 @@ static void pr_cont_pool_info(struct worker_pool *pool) · 4717 unmodified lines | |||
| 4718 | pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); | 4718 | pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice); |
| 4719 | } | 4719 | } |
| 4720 | 4720 | ||
| 4721 | static void pr_cont_work(bool comma, struct work_struct *work) | 4721 | struct pr_cont_work_struct { |
| 4722 | bool comma; | ||
| 4723 | work_func_t func; | ||
| 4724 | long ctr; | ||
| 4725 | }; | ||
| 4726 | |||
| 4727 | static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp) | ||
| 4728 | { | ||
| 4729 | if (!pcwsp->ctr) | ||
| 4730 | goto out_record; | ||
| 4731 | if (func == pcwsp->func) { | ||
| 4732 | pcwsp->ctr++; | ||
| 4733 | return; | ||
| 4734 | } | ||
| 4735 | if (pcwsp->ctr == 1) | ||
| 4736 | pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func); | ||
| 4737 | else | ||
| 4738 | pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func); | ||
| 4739 | pcwsp->ctr = 0; | ||
| 4740 | out_record: | ||
| 4741 | if ((long)func == -1L) | ||
| 4742 | return; | ||
| 4743 | pcwsp->comma = comma; | ||
| 4744 | pcwsp->func = func; | ||
| 4745 | pcwsp->ctr = 1; | ||
| 4746 | } | ||
| 4747 | |||
| 4748 | static void pr_cont_work(bool comma, struct work_struct *work, struct pr_cont_work_struct *pcwsp) | ||
| 4722 | { | 4749 | { |
| 4723 | if (work->func == wq_barrier_func) { | 4750 | if (work->func == wq_barrier_func) { |
| 4724 | struct wq_barrier *barr; | 4751 | struct wq_barrier *barr; |
| 4725 | 4752 | ||
| 4726 | barr = container_of(work, struct wq_barrier, work); | 4753 | barr = container_of(work, struct wq_barrier, work); |
| 4727 | 4754 | ||
| 4755 | pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); | ||
| 4728 | pr_cont("%s BAR(%d)", comma ? "," : "", | 4756 | pr_cont("%s BAR(%d)", comma ? "," : "", |
| 4729 | task_pid_nr(barr->task)); | 4757 | task_pid_nr(barr->task)); |
| 4730 | } else { | 4758 | } else { |
| 4731 | pr_cont("%s %ps", comma ? "," : "", work->func); | 4759 | if (!comma) |
| 4760 | pr_cont_work_flush(comma, (work_func_t)-1, pcwsp); | ||
| 4761 | pr_cont_work_flush(comma, work->func, pcwsp); | ||
| 4732 | } | 4762 | } |
| 4733 | } | 4763 | } |
| 4734 | 4764 | ||
| 4735 | static void show_pwq(struct pool_workqueue *pwq) | 4765 | static void show_pwq(struct pool_workqueue *pwq) |
| 4736 | { | 4766 | { |
| 4767 | struct pr_cont_work_struct pcws = { .ctr = 0, }; | ||
| 4737 | struct worker_pool *pool = pwq->pool; | 4768 | struct worker_pool *pool = pwq->pool; |
| 4738 | struct work_struct *work; | 4769 | struct work_struct *work; |
| 4739 | struct worker *worker; | 4770 | struct worker *worker; |
| @@ -4766,7 +4797,8 @@ static void show_pwq(struct pool_workqueue *pwq) · 26 unmodified lines | |||
| 4766 | worker->rescue_wq ? "(RESCUER)" : "", | 4797 | worker->rescue_wq ? "(RESCUER)" : "", |
| 4767 | worker->current_func); | 4798 | worker->current_func); |
| 4768 | list_for_each_entry(work, &worker->scheduled, entry) | 4799 | list_for_each_entry(work, &worker->scheduled, entry) |
| 4769 | pr_cont_work(false, work); | 4800 | pr_cont_work(false, work, &pcws); |
| 4801 | pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); | ||
| 4770 | comma = true; | 4802 | comma = true; |
| 4771 | } | 4803 | } |
| 4772 | pr_cont("\n"); | 4804 | pr_cont("\n"); |
| @@ -4786,9 +4818,10 @@ static void show_pwq(struct pool_workqueue *pwq) · 13 unmodified lines | |||
| 4786 | if (get_work_pwq(work) != pwq) | 4818 | if (get_work_pwq(work) != pwq) |
| 4787 | continue; | 4819 | continue; |
| 4788 | 4820 | ||
| 4789 | pr_cont_work(comma, work); | 4821 | pr_cont_work(comma, work, &pcws); |
| 4790 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | 4822 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
| 4791 | } | 4823 | } |
| 4824 | pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); | ||
| 4792 | pr_cont("\n"); | 4825 | pr_cont("\n"); |
| 4793 | } | 4826 | } |
| 4794 | 4827 | ||
| @@ -4797,9 +4830,10 @@ static void show_pwq(struct pool_workqueue *pwq) · 2 unmodified lines | |||
| 4797 | 4830 | ||
| 4798 | pr_info(" inactive:"); | 4831 | pr_info(" inactive:"); |
| 4799 | list_for_each_entry(work, &pwq->inactive_works, entry) { | 4832 | list_for_each_entry(work, &pwq->inactive_works, entry) { |
| 4800 | pr_cont_work(comma, work); | 4833 | pr_cont_work(comma, work, &pcws); |
| 4801 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); | 4834 | comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED); |
| 4802 | } | 4835 | } |
| 4836 | pr_cont_work_flush(comma, (work_func_t)-1L, &pcws); | ||
| 4803 | pr_cont("\n"); | 4837 | pr_cont("\n"); |
| 4804 | } | 4838 | } |
| 4805 | } | 4839 | } |