Messages in this thread Patch in this message | | | Date | Thu, 21 Jan 2021 11:17:07 +0100 | From | Peter Zijlstra <> | Subject | [PATCH -v3 5/9] workqueue: Tag bound workers with KTHREAD_IS_PER_CPU |
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Mark the per-cpu workqueue workers as KTHREAD_IS_PER_CPU.
Workqueues have unfortunate semantics in that per-cpu workers are not default flushed and parked during hotplug, however a subset does manual flush on hotplug and hard relies on them for correctness.
Therefore play silly games..
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/workqueue.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1861,6 +1861,8 @@ static void worker_attach_to_pool(struct */ if (pool->flags & POOL_DISASSOCIATED) worker->flags |= WORKER_UNBOUND; + else + kthread_set_per_cpu(worker->task, pool->cpu); list_add_tail(&worker->node, &pool->workers); worker->pool = pool; @@ -1883,6 +1885,7 @@ static void worker_detach_from_pool(stru mutex_lock(&wq_pool_attach_mutex); + kthread_set_per_cpu(worker->task, -1); list_del(&worker->node); worker->pool = NULL; @@ -4919,8 +4922,10 @@ static void unbind_workers(int cpu) raw_spin_unlock_irq(&pool->lock); - for_each_pool_worker(worker, pool) + for_each_pool_worker(worker, pool) { + kthread_set_per_cpu(worker->task, -1); WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0); + } mutex_unlock(&wq_pool_attach_mutex); @@ -4972,9 +4977,11 @@ static void rebind_workers(struct worker * of all workers first and then clear UNBOUND. As we're called * from CPU_ONLINE, the following shouldn't fail. */ - for_each_pool_worker(worker, pool) + for_each_pool_worker(worker, pool) { + kthread_set_per_cpu(worker->task, pool->cpu); WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask) < 0); + } raw_spin_lock_irq(&pool->lock);
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