From 626ab0e69d376fa07599af669af8ba92d58e87c1 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Fri, 23 Jun 2006 02:05:55 -0700 Subject: [PATCH] list: use list_replace_init() instead of list_splice_init() list_splice_init(list, head) does unneeded job if it is known that list_empty(head) == 1. We can use list_replace_init() instead. Signed-off-by: Oleg Nesterov Acked-by: David S. Miller Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/workqueue.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/workqueue.c') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 880fb415a8f6..740c5abceb07 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -531,11 +531,11 @@ int current_is_keventd(void) static void take_over_work(struct workqueue_struct *wq, unsigned int cpu) { struct cpu_workqueue_struct *cwq = per_cpu_ptr(wq->cpu_wq, cpu); - LIST_HEAD(list); + struct list_head list; struct work_struct *work; spin_lock_irq(&cwq->lock); - list_splice_init(&cwq->worklist, &list); + list_replace_init(&cwq->worklist, &list); while (!list_empty(&list)) { printk("Taking work for %s\n", wq->name); -- cgit v1.2.3 From b61367732fc273977cc3fb85c272ce1a7bb1f533 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sun, 25 Jun 2006 05:47:49 -0700 Subject: [PATCH] schedule_on_each_cpu(): reduce kmalloc() size schedule_on_each_cpu() presently does a large kmalloc - 96 kbytes on 1024 CPU 64-bit. Rework it so that we do one 8192-byte allocation and then a pile of tiny ones, via alloc_percpu(). This has a much higher chance of success (100% in the current VM). This also has the effect of reducing the memory requirements from NR_CPUS*n to num_possible_cpus()*n. Cc: Christoph Lameter Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/workqueue.c | 28 ++++++++++++++++++++-------- 1 file changed, 20 insertions(+), 8 deletions(-) (limited to 'kernel/workqueue.c') diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 740c5abceb07..f869aff6bc0c 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -428,22 +428,34 @@ int schedule_delayed_work_on(int cpu, return ret; } -int schedule_on_each_cpu(void (*func) (void *info), void *info) +/** + * schedule_on_each_cpu - call a function on each online CPU from keventd + * @func: the function to call + * @info: a pointer to pass to func() + * + * Returns zero on success. + * Returns -ve errno on failure. + * + * Appears to be racy against CPU hotplug. + * + * schedule_on_each_cpu() is very slow. + */ +int schedule_on_each_cpu(void (*func)(void *info), void *info) { int cpu; - struct work_struct *work; + struct work_struct *works; - work = kmalloc(NR_CPUS * sizeof(struct work_struct), GFP_KERNEL); - - if (!work) + works = alloc_percpu(struct work_struct); + if (!works) return -ENOMEM; + for_each_online_cpu(cpu) { - INIT_WORK(work + cpu, func, info); + INIT_WORK(per_cpu_ptr(works, cpu), func, info); __queue_work(per_cpu_ptr(keventd_wq->cpu_wq, cpu), - work + cpu); + per_cpu_ptr(works, cpu)); } flush_workqueue(keventd_wq); - kfree(work); + free_percpu(works); return 0; } -- cgit v1.2.3 From fc75cdfa5b43ac4d3232b490800cd35063adafd3 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Sun, 25 Jun 2006 05:49:10 -0700 Subject: [PATCH] cpu hotplug: fix CPU_UP_CANCEL handling If a cpu hotplug callback fails on CPU_UP_PREPARE, all callbacks will be called with CPU_UP_CANCELED. A few of these callbacks assume that on CPU_UP_PREPARE a pointer to task has been stored in a percpu array. This assumption is not true if CPU_UP_PREPARE fails and the following calls to kthread_bind() in CPU_UP_CANCELED will cause an addressing exception because of passing a NULL pointer. Signed-off-by: Heiko Carstens Cc: Ashok Raj Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sched.c | 2 ++ kernel/softirq.c | 2 ++ kernel/softlockup.c | 2 ++ kernel/workqueue.c | 2 ++ 4 files changed, 8 insertions(+) (limited to 'kernel/workqueue.c') diff --git a/kernel/sched.c b/kernel/sched.c index f8d540b324ca..f06d059edef5 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -4756,6 +4756,8 @@ static int migration_call(struct notifier_block *nfb, unsigned long action, break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: + if (!cpu_rq(cpu)->migration_thread) + break; /* Unbind it from offline cpu so it can run. Fall thru. */ kthread_bind(cpu_rq(cpu)->migration_thread, any_online_cpu(cpu_online_map)); diff --git a/kernel/softirq.c b/kernel/softirq.c index 336f92d64e2e..9e2f1c6e73d7 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -470,6 +470,8 @@ static int cpu_callback(struct notifier_block *nfb, break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: + if (!per_cpu(ksoftirqd, hotcpu)) + break; /* Unbind so it can run. Fall thru. */ kthread_bind(per_cpu(ksoftirqd, hotcpu), any_online_cpu(cpu_online_map)); diff --git a/kernel/softlockup.c b/kernel/softlockup.c index 2c1be1163edc..b5c3b94e01ce 100644 --- a/kernel/softlockup.c +++ b/kernel/softlockup.c @@ -127,6 +127,8 @@ cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) break; #ifdef CONFIG_HOTPLUG_CPU case CPU_UP_CANCELED: + if (!per_cpu(watchdog_task, hotcpu)) + break; /* Unbind so it can run. Fall thru. */ kthread_bind(per_cpu(watchdog_task, hotcpu), any_online_cpu(cpu_online_map)); diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f869aff6bc0c..565cf7a1febd 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -590,6 +590,8 @@ static int workqueue_cpu_callback(struct notifier_block *nfb, case CPU_UP_CANCELED: list_for_each_entry(wq, &workqueues, list) { + if (!per_cpu_ptr(wq->cpu_wq, hotcpu)->thread) + continue; /* Unbind so it can run. */ kthread_bind(per_cpu_ptr(wq->cpu_wq, hotcpu)->thread, any_online_cpu(cpu_online_map)); -- cgit v1.2.3