Doug / smarc-fsl-linux-kernel

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Commit 9b41ea7289a589993d3daabc61f999b4147872c4

Authored by Andrew Morton
Committed by Greg Kroah-Hartman
1 parent 2b25742556
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

[PATCH] workqueue: remove lock_cpu_hotplug() 

Use a private lock instead.  It protects all per-cpu data structures in
workqueue.c, including the workqueues list.

Fix a bug in schedule_on_each_cpu(): it was forgetting to lock down the
per-cpu resources.

Unfixed long-standing bug: if someone unplugs the CPU identified by
`singlethread_cpu' the kernel will get very sick.

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Showing 1 changed file with 21 additions and 12 deletions Side-by-side Diff

... ... @@ -68,7 +68,7 @@
68 68  
69 69 /* All the per-cpu workqueues on the system, for hotplug cpu to add/remove
70 70 threads to each one as cpus come/go. */
71   -static DEFINE_SPINLOCK(workqueue_lock);
  71 +static DEFINE_MUTEX(workqueue_mutex);
72 72 static LIST_HEAD(workqueues);
73 73  
74 74 static int singlethread_cpu;
75 75  
... ... @@ -320,10 +320,10 @@
320 320 } else {
321 321 int cpu;
322 322  
323   - lock_cpu_hotplug();
  323 + mutex_lock(&workqueue_mutex);
324 324 for_each_online_cpu(cpu)
325 325 flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu));
326   - unlock_cpu_hotplug();
  326 + mutex_unlock(&workqueue_mutex);
327 327 }
328 328 }
329 329 EXPORT_SYMBOL_GPL(flush_workqueue);
... ... @@ -371,8 +371,7 @@
371 371 }
372 372  
373 373 wq->name = name;
374   - /* We don't need the distraction of CPUs appearing and vanishing. */
375   - lock_cpu_hotplug();
  374 + mutex_lock(&workqueue_mutex);
376 375 if (singlethread) {
377 376 INIT_LIST_HEAD(&wq->list);
378 377 p = create_workqueue_thread(wq, singlethread_cpu);
379 378  
... ... @@ -381,9 +380,7 @@
381 380 else
382 381 wake_up_process(p);
383 382 } else {
384   - spin_lock(&workqueue_lock);
385 383 list_add(&wq->list, &workqueues);
386   - spin_unlock(&workqueue_lock);
387 384 for_each_online_cpu(cpu) {
388 385 p = create_workqueue_thread(wq, cpu);
389 386 if (p) {
... ... @@ -393,7 +390,7 @@
393 390 destroy = 1;
394 391 }
395 392 }
396   - unlock_cpu_hotplug();
  393 + mutex_unlock(&workqueue_mutex);
397 394  
398 395 /*
399 396 * Was there any error during startup? If yes then clean up:
400 397  
401 398  
402 399  
... ... @@ -434,17 +431,15 @@
434 431 flush_workqueue(wq);
435 432  
436 433 /* We don't need the distraction of CPUs appearing and vanishing. */
437   - lock_cpu_hotplug();
  434 + mutex_lock(&workqueue_mutex);
438 435 if (is_single_threaded(wq))
439 436 cleanup_workqueue_thread(wq, singlethread_cpu);
440 437 else {
441 438 for_each_online_cpu(cpu)
442 439 cleanup_workqueue_thread(wq, cpu);
443   - spin_lock(&workqueue_lock);
444 440 list_del(&wq->list);
445   - spin_unlock(&workqueue_lock);
446 441 }
447   - unlock_cpu_hotplug();
  442 + mutex_unlock(&workqueue_mutex);
448 443 free_percpu(wq->cpu_wq);
449 444 kfree(wq);
450 445 }
451 446  
... ... @@ -515,11 +510,13 @@
515 510 if (!works)
516 511 return -ENOMEM;
517 512  
  513 + mutex_lock(&workqueue_mutex);
518 514 for_each_online_cpu(cpu) {
519 515 INIT_WORK(per_cpu_ptr(works, cpu), func, info);
520 516 __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu),
521 517 per_cpu_ptr(works, cpu));
522 518 }
  519 + mutex_unlock(&workqueue_mutex);
523 520 flush_workqueue(keventd_wq);
524 521 free_percpu(works);
525 522 return 0;
... ... @@ -635,6 +632,7 @@
635 632  
636 633 switch (action) {
637 634 case CPU_UP_PREPARE:
  635 + mutex_lock(&workqueue_mutex);
638 636 /* Create a new workqueue thread for it. */
639 637 list_for_each_entry(wq, &workqueues, list) {
640 638 if (!create_workqueue_thread(wq, hotcpu)) {
... ... @@ -653,6 +651,7 @@
653 651 kthread_bind(cwq->thread, hotcpu);
654 652 wake_up_process(cwq->thread);
655 653 }
  654 + mutex_unlock(&workqueue_mutex);
656 655 break;
657 656  
658 657 case CPU_UP_CANCELED:
659 658  
660 659  
... ... @@ -664,13 +663,23 @@
664 663 any_online_cpu(cpu_online_map));
665 664 cleanup_workqueue_thread(wq, hotcpu);
666 665 }
  666 + mutex_unlock(&workqueue_mutex);
667 667 break;
668 668  
  669 + case CPU_DOWN_PREPARE:
  670 + mutex_lock(&workqueue_mutex);
  671 + break;
  672 +
  673 + case CPU_DOWN_FAILED:
  674 + mutex_unlock(&workqueue_mutex);
  675 + break;
  676 +
669 677 case CPU_DEAD:
670 678 list_for_each_entry(wq, &workqueues, list)
671 679 cleanup_workqueue_thread(wq, hotcpu);
672 680 list_for_each_entry(wq, &workqueues, list)
673 681 take_over_work(wq, hotcpu);
  682 + mutex_unlock(&workqueue_mutex);
674 683 break;
675 684 }
676 685