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authorNathan Lynch <ntl@pobox.com>2006-01-08 01:05:12 -0800
committerChris Wright <chrisw@sous-sol.org>2006-01-14 22:15:28 -0800
commit4e5ae24c6485ea49e61bdafb3e4d4d598bf5b1dc (patch)
tree20368dec5ce92a15f182bebc4a68e41924c57e7b
parent2d7fc97cea8a45158bc6428a3f99782e41e6b5c3 (diff)
downloadlinux-linaro-stable-4e5ae24c6485ea49e61bdafb3e4d4d598bf5b1dc.tar.gz
[PATCH] fix workqueue oops during cpu offline
Use first_cpu(cpu_possible_map) for the single-thread workqueue case. We used to hardcode 0, but that broke on systems where !cpu_possible(0) when workqueue_struct->cpu_workqueue_struct was changed from a static array to alloc_percpu. Commit id bce61dd49d6ba7799be2de17c772e4c701558f14 ("Fix hardcoded cpu=0 in workqueue for per_cpu_ptr() calls") fixed that for Ben's funky sparc64 system, but it regressed my Power5. Offlining cpu 0 oopses upon the next call to queue_work for a single-thread workqueue, because now we try to manipulate per_cpu_ptr(wq->cpu_wq, 1), which is uninitialized. So we need to establish an unchanging "slot" for single-thread workqueues which will have a valid percpu allocation. Since alloc_percpu keys off of cpu_possible_map, which must not change after initialization, make this slot == first_cpu(cpu_possible_map). Signed-off-by: Nathan Lynch <ntl@pobox.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
-rw-r--r--kernel/workqueue.c16
1 files changed, 10 insertions, 6 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 2bd5aee1c736..d3123c25557e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -29,7 +29,8 @@
#include <linux/kthread.h>
/*
- * The per-CPU workqueue (if single thread, we always use cpu 0's).
+ * The per-CPU workqueue (if single thread, we always use the first
+ * possible cpu).
*
* The sequence counters are for flush_scheduled_work(). It wants to wait
* until until all currently-scheduled works are completed, but it doesn't
@@ -69,6 +70,8 @@ struct workqueue_struct {
static DEFINE_SPINLOCK(workqueue_lock);
static LIST_HEAD(workqueues);
+static int singlethread_cpu;
+
/* If it's single threaded, it isn't in the list of workqueues. */
static inline int is_single_threaded(struct workqueue_struct *wq)
{
@@ -102,7 +105,7 @@ int fastcall queue_work(struct workqueue_struct *wq, struct work_struct *work)
if (!test_and_set_bit(0, &work->pending)) {
if (unlikely(is_single_threaded(wq)))
- cpu = any_online_cpu(cpu_online_map);
+ cpu = singlethread_cpu;
BUG_ON(!list_empty(&work->entry));
__queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
ret = 1;
@@ -118,7 +121,7 @@ static void delayed_work_timer_fn(unsigned long __data)
int cpu = smp_processor_id();
if (unlikely(is_single_threaded(wq)))
- cpu = any_online_cpu(cpu_online_map);
+ cpu = singlethread_cpu;
__queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
}
@@ -267,7 +270,7 @@ void fastcall flush_workqueue(struct workqueue_struct *wq)
if (is_single_threaded(wq)) {
/* Always use first cpu's area. */
- flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, any_online_cpu(cpu_online_map)));
+ flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, singlethread_cpu));
} else {
int cpu;
@@ -320,7 +323,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
lock_cpu_hotplug();
if (singlethread) {
INIT_LIST_HEAD(&wq->list);
- p = create_workqueue_thread(wq, any_online_cpu(cpu_online_map));
+ p = create_workqueue_thread(wq, singlethread_cpu);
if (!p)
destroy = 1;
else
@@ -374,7 +377,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
/* We don't need the distraction of CPUs appearing and vanishing. */
lock_cpu_hotplug();
if (is_single_threaded(wq))
- cleanup_workqueue_thread(wq, any_online_cpu(cpu_online_map));
+ cleanup_workqueue_thread(wq, singlethread_cpu);
else {
for_each_online_cpu(cpu)
cleanup_workqueue_thread(wq, cpu);
@@ -543,6 +546,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
void init_workqueues(void)
{
+ singlethread_cpu = first_cpu(cpu_possible_map);
hotcpu_notifier(workqueue_cpu_callback, 0);
keventd_wq = create_workqueue("events");
BUG_ON(!keventd_wq);