Commit bce61dd4 authored by Ben Collins's avatar Ben Collins Committed by Linus Torvalds
Browse files

[PATCH] Fix hardcoded cpu=0 in workqueue for per_cpu_ptr() calls

Tracked this down on an Ultra Enterprise 3000.  It's a 6-way machine.  Odd
thing about this machine (and it's good for finding bugs like this) is that
the CPU id's are not 0 based.  For instance, on my machine the CPU's are

This caused some NULL pointer dereference in kernel/workqueue.c because for
single_threaded workqueue's, it hardcoded the cpu to 0.

I changed the 0's to any_online_cpu(cpu_online_mask), which cpumask.h
claims is "First cpu in mask".  So this fits the same usage.

Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent ee500f27
......@@ -102,7 +102,7 @@ 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 = 0;
cpu = any_online_cpu(cpu_online_map);
__queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
ret = 1;
......@@ -118,7 +118,7 @@ static void delayed_work_timer_fn(unsigned long __data)
int cpu = smp_processor_id();
if (unlikely(is_single_threaded(wq)))
cpu = 0;
cpu = any_online_cpu(cpu_online_map);
__queue_work(per_cpu_ptr(wq->cpu_wq, cpu), work);
......@@ -266,8 +266,8 @@ void fastcall flush_workqueue(struct workqueue_struct *wq)
if (is_single_threaded(wq)) {
/* Always use cpu 0's area. */
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, 0));
/* Always use first cpu's area. */
flush_cpu_workqueue(per_cpu_ptr(wq->cpu_wq, any_online_cpu(cpu_online_map)));
} else {
int cpu;
......@@ -320,7 +320,7 @@ struct workqueue_struct *__create_workqueue(const char *name,
if (singlethread) {
p = create_workqueue_thread(wq, 0);
p = create_workqueue_thread(wq, any_online_cpu(cpu_online_map));
if (!p)
destroy = 1;
......@@ -374,7 +374,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
/* We don't need the distraction of CPUs appearing and vanishing. */
if (is_single_threaded(wq))
cleanup_workqueue_thread(wq, 0);
cleanup_workqueue_thread(wq, any_online_cpu(cpu_online_map));
else {
cleanup_workqueue_thread(wq, cpu);
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