From 436c3539b5d3b39dccf769a3627cb94ecb075698 Mon Sep 17 00:00:00 2001 Message-Id: <436c3539b5d3b39dccf769a3627cb94ecb075698.1596234183.git.zanussi@kernel.org> In-Reply-To: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org> References: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org> From: Julia Cartwright Date: Fri, 28 Sep 2018 21:03:51 +0000 Subject: [PATCH 009/329] kthread: convert worker lock to raw spinlock Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.135-rt60.tar.xz In order to enable the queuing of kthread work items from hardirq context even when PREEMPT_RT_FULL is enabled, convert the worker spin_lock to a raw_spin_lock. This is only acceptable to do because the work performed under the lock is well-bounded and minimal. Cc: Sebastian Andrzej Siewior Cc: Guenter Roeck Reported-and-tested-by: Steffen Trumtrar Reported-by: Tim Sander Signed-off-by: Julia Cartwright Signed-off-by: Sebastian Andrzej Siewior --- include/linux/kthread.h | 2 +- kernel/kthread.c | 42 ++++++++++++++++++++--------------------- 2 files changed, 22 insertions(+), 22 deletions(-) diff --git a/include/linux/kthread.h b/include/linux/kthread.h index c1961761311d..ad292898f7f2 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -85,7 +85,7 @@ enum { struct kthread_worker { unsigned int flags; - spinlock_t lock; + raw_spinlock_t lock; struct list_head work_list; struct list_head delayed_work_list; struct task_struct *task; diff --git a/kernel/kthread.c b/kernel/kthread.c index 087d18d771b5..5641b55783a6 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -599,7 +599,7 @@ void __kthread_init_worker(struct kthread_worker *worker, struct lock_class_key *key) { memset(worker, 0, sizeof(struct kthread_worker)); - spin_lock_init(&worker->lock); + raw_spin_lock_init(&worker->lock); lockdep_set_class_and_name(&worker->lock, key, name); INIT_LIST_HEAD(&worker->work_list); INIT_LIST_HEAD(&worker->delayed_work_list); @@ -641,21 +641,21 @@ int kthread_worker_fn(void *worker_ptr) if (kthread_should_stop()) { __set_current_state(TASK_RUNNING); - spin_lock_irq(&worker->lock); + raw_spin_lock_irq(&worker->lock); worker->task = NULL; - spin_unlock_irq(&worker->lock); + raw_spin_unlock_irq(&worker->lock); return 0; } work = NULL; - spin_lock_irq(&worker->lock); + raw_spin_lock_irq(&worker->lock); if (!list_empty(&worker->work_list)) { work = list_first_entry(&worker->work_list, struct kthread_work, node); list_del_init(&work->node); } worker->current_work = work; - spin_unlock_irq(&worker->lock); + raw_spin_unlock_irq(&worker->lock); if (work) { __set_current_state(TASK_RUNNING); @@ -812,12 +812,12 @@ bool kthread_queue_work(struct kthread_worker *worker, bool ret = false; unsigned long flags; - spin_lock_irqsave(&worker->lock, flags); + raw_spin_lock_irqsave(&worker->lock, flags); if (!queuing_blocked(worker, work)) { kthread_insert_work(worker, work, &worker->work_list); ret = true; } - spin_unlock_irqrestore(&worker->lock, flags); + raw_spin_unlock_irqrestore(&worker->lock, flags); return ret; } EXPORT_SYMBOL_GPL(kthread_queue_work); @@ -843,7 +843,7 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) if (WARN_ON_ONCE(!worker)) return; - spin_lock(&worker->lock); + raw_spin_lock(&worker->lock); /* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); @@ -852,7 +852,7 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) list_del_init(&work->node); kthread_insert_work(worker, work, &worker->work_list); - spin_unlock(&worker->lock); + raw_spin_unlock(&worker->lock); } EXPORT_SYMBOL(kthread_delayed_work_timer_fn); @@ -908,14 +908,14 @@ bool kthread_queue_delayed_work(struct kthread_worker *worker, unsigned long flags; bool ret = false; - spin_lock_irqsave(&worker->lock, flags); + raw_spin_lock_irqsave(&worker->lock, flags); if (!queuing_blocked(worker, work)) { __kthread_queue_delayed_work(worker, dwork, delay); ret = true; } - spin_unlock_irqrestore(&worker->lock, flags); + raw_spin_unlock_irqrestore(&worker->lock, flags); return ret; } EXPORT_SYMBOL_GPL(kthread_queue_delayed_work); @@ -951,7 +951,7 @@ void kthread_flush_work(struct kthread_work *work) if (!worker) return; - spin_lock_irq(&worker->lock); + raw_spin_lock_irq(&worker->lock); /* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); @@ -963,7 +963,7 @@ void kthread_flush_work(struct kthread_work *work) else noop = true; - spin_unlock_irq(&worker->lock); + raw_spin_unlock_irq(&worker->lock); if (!noop) wait_for_completion(&fwork.done); @@ -996,9 +996,9 @@ static bool __kthread_cancel_work(struct kthread_work *work, bool is_dwork, * any queuing is blocked by setting the canceling counter. */ work->canceling++; - spin_unlock_irqrestore(&worker->lock, *flags); + raw_spin_unlock_irqrestore(&worker->lock, *flags); del_timer_sync(&dwork->timer); - spin_lock_irqsave(&worker->lock, *flags); + raw_spin_lock_irqsave(&worker->lock, *flags); work->canceling--; } @@ -1045,7 +1045,7 @@ bool kthread_mod_delayed_work(struct kthread_worker *worker, unsigned long flags; int ret = false; - spin_lock_irqsave(&worker->lock, flags); + raw_spin_lock_irqsave(&worker->lock, flags); /* Do not bother with canceling when never queued. */ if (!work->worker) @@ -1062,7 +1062,7 @@ bool kthread_mod_delayed_work(struct kthread_worker *worker, fast_queue: __kthread_queue_delayed_work(worker, dwork, delay); out: - spin_unlock_irqrestore(&worker->lock, flags); + raw_spin_unlock_irqrestore(&worker->lock, flags); return ret; } EXPORT_SYMBOL_GPL(kthread_mod_delayed_work); @@ -1076,7 +1076,7 @@ static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) if (!worker) goto out; - spin_lock_irqsave(&worker->lock, flags); + raw_spin_lock_irqsave(&worker->lock, flags); /* Work must not be used with >1 worker, see kthread_queue_work(). */ WARN_ON_ONCE(work->worker != worker); @@ -1090,13 +1090,13 @@ static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork) * In the meantime, block any queuing by setting the canceling counter. */ work->canceling++; - spin_unlock_irqrestore(&worker->lock, flags); + raw_spin_unlock_irqrestore(&worker->lock, flags); kthread_flush_work(work); - spin_lock_irqsave(&worker->lock, flags); + raw_spin_lock_irqsave(&worker->lock, flags); work->canceling--; out_fast: - spin_unlock_irqrestore(&worker->lock, flags); + raw_spin_unlock_irqrestore(&worker->lock, flags); out: return ret; } -- 2.17.1