Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423239AbWJZKys (ORCPT ); Thu, 26 Oct 2006 06:54:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423248AbWJZKyr (ORCPT ); Thu, 26 Oct 2006 06:54:47 -0400 Received: from ausmtp04.au.ibm.com ([202.81.18.152]:37584 "EHLO ausmtp04.au.ibm.com") by vger.kernel.org with ESMTP id S1423239AbWJZKyq (ORCPT ); Thu, 26 Oct 2006 06:54:46 -0400 Date: Thu, 26 Oct 2006 16:25:23 +0530 From: Gautham R Shenoy To: Gautham R Shenoy Cc: rusty@rustcorp.com.au, torvalds@osdl.org, mingo@elte.hu, akpm@osdl.org, linux-kernel@vger.kernel.org, paulmck@us.ibm.com, vatsa@in.ibm.com, dipankar@in.ibm.com, gaughen@us.ibm.com, arjan@linux.intel.org, davej@redhat.com, venkatesh.pallipadi@intel.com, kiran@scalex86.org Subject: [PATCH 3/5] lock_cpu_hotplug:Redesign - Use lock_cpu_hotplug in workqueue.c instead of workqueue_mutex. Message-ID: <20061026105523.GD11803@in.ibm.com> Reply-To: ego@in.ibm.com References: <20061026104858.GA11803@in.ibm.com> <20061026105058.GB11803@in.ibm.com> <20061026105342.GC11803@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061026105342.GC11803@in.ibm.com> User-Agent: Mutt/1.5.10i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4400 Lines: 153 Use lock_cpu_hotplug() instead of workqueue_mutex to prevent a cpu-hotplug event in kernel/workqueue.c. Signed-off-by: Gautham R Shenoy --- 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. 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