Messages in this thread Patch in this message | | | Date | Thu, 26 Oct 2006 16:25:23 +0530 | From | Gautham R Shenoy <> | Subject | [PATCH 3/5] lock_cpu_hotplug:Redesign - Use lock_cpu_hotplug in workqueue.c instead of workqueue_mutex. |
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Use lock_cpu_hotplug() instead of workqueue_mutex to prevent a cpu-hotplug event in kernel/workqueue.c.
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
--- kernel/workqueue.c | 37 +++++++++++++------------------------ 1 files changed, 13 insertions(+), 24 deletions(-)
Index: hotplug/kernel/workqueue.c =================================================================== --- hotplug.orig/kernel/workqueue.c +++ hotplug/kernel/workqueue.c @@ -67,9 +67,7 @@ struct workqueue_struct { struct list_head list; /* Empty if single thread */ }; -/* All the per-cpu workqueues on the system, for hotplug cpu to add/remove - threads to each one as cpus come/go. */ -static DEFINE_MUTEX(workqueue_mutex); +static DEFINE_SPINLOCK(workqueue_lock); static LIST_HEAD(workqueues); static int singlethread_cpu; @@ -328,10 +326,10 @@ void fastcall flush_workqueue(struct wor } else { int cpu; - mutex_lock(&workqueue_mutex); + lock_cpu_hotplug(); for_each_online_cpu(cpu) flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, cpu)); - mutex_unlock(&workqueue_mutex); + unlock_cpu_hotplug(); } } EXPORT_SYMBOL_GPL(flush_workqueue); @@ -379,7 +377,7 @@ struct workqueue_struct *__create_workqu } wq->name = name; - mutex_lock(&workqueue_mutex); + lock_cpu_hotplug(); if (singlethread) { INIT_LIST_HEAD(&wq->list); p = create_workqueue_thread(wq, singlethread_cpu); @@ -388,7 +386,9 @@ struct workqueue_struct *__create_workqu else wake_up_process(p); } else { + spin_lock(&workqueue_lock); list_add(&wq->list, &workqueues); + spin_unlock(&workqueue_lock); for_each_online_cpu(cpu) { p = create_workqueue_thread(wq, cpu); if (p) { @@ -398,8 +398,7 @@ struct workqueue_struct *__create_workqu destroy = 1; } } - mutex_unlock(&workqueue_mutex); - + unlock_cpu_hotplug(); /* * Was there any error during startup? If yes then clean up: */ @@ -439,15 +438,17 @@ void destroy_workqueue(struct workqueue_ flush_workqueue(wq); /* We don't need the distraction of CPUs appearing and vanishing. */ - mutex_lock(&workqueue_mutex); + lock_cpu_hotplug(); if (is_single_threaded(wq)) cleanup_workqueue_thread(wq, singlethread_cpu); else { for_each_online_cpu(cpu) cleanup_workqueue_thread(wq, cpu); + spin_lock(&workqueue_lock); list_del(&wq->list); + spin_unlock(&workqueue_lock); } - mutex_unlock(&workqueue_mutex); + unlock_cpu_hotplug(); free_percpu(wq->cpu_wq); kfree(wq); } @@ -519,13 +520,13 @@ int schedule_on_each_cpu(void (*func)(vo if (!works) return -ENOMEM; - mutex_lock(&workqueue_mutex); + lock_cpu_hotplug(); for_each_online_cpu(cpu) { INIT_WORK(per_cpu_ptr(works, cpu), func, info); __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), per_cpu_ptr(works, cpu)); } - mutex_unlock(&workqueue_mutex); + unlock_cpu_hotplug(); flush_workqueue(keventd_wq); free_percpu(works); return 0; @@ -641,7 +642,6 @@ static int __devinit workqueue_cpu_callb switch (action) { case CPU_UP_PREPARE: - mutex_lock(&workqueue_mutex); /* Create a new workqueue thread for it. */ list_for_each_entry(wq, &workqueues, list) { if (!create_workqueue_thread(wq, hotcpu)) { @@ -660,7 +660,6 @@ static int __devinit workqueue_cpu_callb kthread_bind(cwq->thread, hotcpu); wake_up_process(cwq->thread); } - mutex_unlock(&workqueue_mutex); break; case CPU_UP_CANCELED: @@ -672,15 +671,6 @@ static int __devinit workqueue_cpu_callb any_online_cpu(cpu_online_map)); cleanup_workqueue_thread(wq, hotcpu); } - mutex_unlock(&workqueue_mutex); - break; - - case CPU_DOWN_PREPARE: - mutex_lock(&workqueue_mutex); - break; - - case CPU_DOWN_FAILED: - mutex_unlock(&workqueue_mutex); break; case CPU_DEAD: @@ -688,7 +678,6 @@ static int __devinit workqueue_cpu_callb cleanup_workqueue_thread(wq, hotcpu); list_for_each_entry(wq, &workqueues, list) take_over_work(wq, hotcpu); - mutex_unlock(&workqueue_mutex); break; } -- Gautham R Shenoy Linux Technology Center IBM India. "Freedom comes with a price tag of responsibility, which is still a bargain, because Freedom is priceless!" - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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