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* [PATCH] io-wq: wqe and worker locks no longer need to be IRQ safe
@ 2021-08-30 14:02 Jens Axboe
  0 siblings, 0 replies; only message in thread
From: Jens Axboe @ 2021-08-30 14:02 UTC (permalink / raw)
  To: io-uring

io_uring no longer queues async work off completion handlers that run in
hard or soft interrupt context, and that use case was the only reason that
io-wq had to use IRQ safe locks for wqe and worker locks.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

---

diff --git a/fs/io-wq.c b/fs/io-wq.c
index da3ad45028f9..13aeb48a0964 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -178,7 +178,7 @@ static void io_worker_exit(struct io_worker *worker)
 		complete(&worker->ref_done);
 	wait_for_completion(&worker->ref_done);
 
-	raw_spin_lock_irq(&wqe->lock);
+	raw_spin_lock(&wqe->lock);
 	if (worker->flags & IO_WORKER_F_FREE)
 		hlist_nulls_del_rcu(&worker->nulls_node);
 	list_del_rcu(&worker->all_list);
@@ -188,7 +188,7 @@ static void io_worker_exit(struct io_worker *worker)
 	worker->flags = 0;
 	current->flags &= ~PF_IO_WORKER;
 	preempt_enable();
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 
 	kfree_rcu(worker, rcu);
 	io_worker_ref_put(wqe->wq);
@@ -254,14 +254,14 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
 	if (!ret) {
 		bool do_create = false, first = false;
 
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		if (acct->nr_workers < acct->max_workers) {
 			if (!acct->nr_workers)
 				first = true;
 			acct->nr_workers++;
 			do_create = true;
 		}
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		if (do_create) {
 			atomic_inc(&acct->nr_running);
 			atomic_inc(&wqe->wq->worker_refs);
@@ -289,14 +289,14 @@ static void create_worker_cb(struct callback_head *cb)
 	wqe = worker->wqe;
 	wq = wqe->wq;
 	acct = &wqe->acct[worker->create_index];
-	raw_spin_lock_irq(&wqe->lock);
+	raw_spin_lock(&wqe->lock);
 	if (acct->nr_workers < acct->max_workers) {
 		if (!acct->nr_workers)
 			first = true;
 		acct->nr_workers++;
 		do_create = true;
 	}
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 	if (do_create) {
 		create_io_worker(wq, wqe, worker->create_index, first);
 	} else {
@@ -510,9 +510,9 @@ static void io_assign_current_work(struct io_worker *worker,
 		cond_resched();
 	}
 
-	spin_lock_irq(&worker->lock);
+	spin_lock(&worker->lock);
 	worker->cur_work = work;
-	spin_unlock_irq(&worker->lock);
+	spin_unlock(&worker->lock);
 }
 
 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
@@ -542,7 +542,7 @@ static void io_worker_handle_work(struct io_worker *worker)
 		else if (stalled)
 			wqe->flags |= IO_WQE_FLAG_STALLED;
 
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		if (!work)
 			break;
 		io_assign_current_work(worker, work);
@@ -574,16 +574,16 @@ static void io_worker_handle_work(struct io_worker *worker)
 				clear_bit(hash, &wq->hash->map);
 				if (wq_has_sleeper(&wq->hash->wait))
 					wake_up(&wq->hash->wait);
-				raw_spin_lock_irq(&wqe->lock);
+				raw_spin_lock(&wqe->lock);
 				wqe->flags &= ~IO_WQE_FLAG_STALLED;
 				/* skip unnecessary unlock-lock wqe->lock */
 				if (!work)
 					goto get_next;
-				raw_spin_unlock_irq(&wqe->lock);
+				raw_spin_unlock(&wqe->lock);
 			}
 		} while (work);
 
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 	} while (1);
 }
 
@@ -604,13 +604,13 @@ static int io_wqe_worker(void *data)
 
 		set_current_state(TASK_INTERRUPTIBLE);
 loop:
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		if (io_wqe_run_queue(wqe)) {
 			io_worker_handle_work(worker);
 			goto loop;
 		}
 		__io_worker_idle(wqe, worker);
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		if (io_flush_signals())
 			continue;
 		ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
@@ -629,7 +629,7 @@ static int io_wqe_worker(void *data)
 	}
 
 	if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		io_worker_handle_work(worker);
 	}
 
@@ -671,9 +671,9 @@ void io_wq_worker_sleeping(struct task_struct *tsk)
 
 	worker->flags &= ~IO_WORKER_F_RUNNING;
 
-	raw_spin_lock_irq(&worker->wqe->lock);
+	raw_spin_lock(&worker->wqe->lock);
 	io_wqe_dec_running(worker);
-	raw_spin_unlock_irq(&worker->wqe->lock);
+	raw_spin_unlock(&worker->wqe->lock);
 }
 
 static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first)
@@ -699,9 +699,9 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bo
 		kfree(worker);
 fail:
 		atomic_dec(&acct->nr_running);
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		acct->nr_workers--;
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		io_worker_ref_put(wq);
 		return;
 	}
@@ -711,7 +711,7 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bo
 	set_cpus_allowed_ptr(tsk, wqe->cpu_mask);
 	tsk->flags |= PF_NO_SETAFFINITY;
 
-	raw_spin_lock_irq(&wqe->lock);
+	raw_spin_lock(&wqe->lock);
 	hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
 	list_add_tail_rcu(&worker->all_list, &wqe->all_list);
 	worker->flags |= IO_WORKER_F_FREE;
@@ -719,7 +719,7 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bo
 		worker->flags |= IO_WORKER_F_BOUND;
 	if (first && (worker->flags & IO_WORKER_F_BOUND))
 		worker->flags |= IO_WORKER_F_FIXED;
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 	wake_up_new_task(tsk);
 }
 
@@ -795,7 +795,6 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
 {
 	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
 	int work_flags;
-	unsigned long flags;
 
 	/*
 	 * If io-wq is exiting for this task, or if the request has explicitly
@@ -808,10 +807,10 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
 	}
 
 	work_flags = work->flags;
-	raw_spin_lock_irqsave(&wqe->lock, flags);
+	raw_spin_lock(&wqe->lock);
 	io_wqe_insert_work(wqe, work);
 	wqe->flags &= ~IO_WQE_FLAG_STALLED;
-	raw_spin_unlock_irqrestore(&wqe->lock, flags);
+	raw_spin_unlock(&wqe->lock);
 
 	if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
 	    !atomic_read(&acct->nr_running))
@@ -840,19 +839,18 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
 {
 	struct io_cb_cancel_data *match = data;
-	unsigned long flags;
 
 	/*
 	 * Hold the lock to avoid ->cur_work going out of scope, caller
 	 * may dereference the passed in work.
 	 */
-	spin_lock_irqsave(&worker->lock, flags);
+	spin_lock(&worker->lock);
 	if (worker->cur_work &&
 	    match->fn(worker->cur_work, match->data)) {
 		set_notify_signal(worker->task);
 		match->nr_running++;
 	}
-	spin_unlock_irqrestore(&worker->lock, flags);
+	spin_unlock(&worker->lock);
 
 	return match->nr_running && !match->cancel_all;
 }
@@ -880,16 +878,15 @@ static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
 {
 	struct io_wq_work_node *node, *prev;
 	struct io_wq_work *work;
-	unsigned long flags;
 
 retry:
-	raw_spin_lock_irqsave(&wqe->lock, flags);
+	raw_spin_lock(&wqe->lock);
 	wq_list_for_each(node, prev, &wqe->work_list) {
 		work = container_of(node, struct io_wq_work, list);
 		if (!match->fn(work, match->data))
 			continue;
 		io_wqe_remove_pending(wqe, work, prev);
-		raw_spin_unlock_irqrestore(&wqe->lock, flags);
+		raw_spin_unlock(&wqe->lock);
 		io_run_cancel(work, wqe);
 		match->nr_pending++;
 		if (!match->cancel_all)
@@ -898,7 +895,7 @@ static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
 		/* not safe to continue after unlock */
 		goto retry;
 	}
-	raw_spin_unlock_irqrestore(&wqe->lock, flags);
+	raw_spin_unlock(&wqe->lock);
 }
 
 static void io_wqe_cancel_running_work(struct io_wqe *wqe,

-- 
Jens Axboe


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