[PATCH 05/11] io-wq: add a new parameter for creating a new fixed worker

[Hao Xu <hao.xu@xxxxxxxxx>]

From: Hao Xu <howeyxu@xxxxxxxxxxx>

Add a new parameter when creating new workers to indicate if users
want a normal or fixed worker.

Signed-off-by: Hao Xu <howeyxu@xxxxxxxxxxx>
---
 io_uring/io-wq.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index bf9e9af8d9ca..048856eef4d4 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -137,7 +137,7 @@ struct io_cb_cancel_data {
 	bool cancel_all;
 };
 
-static bool create_io_worker(struct io_wq *wq, int index);
+static bool create_io_worker(struct io_wq *wq, int index, bool fixed);
 static void io_wq_dec_running(struct io_worker *worker);
 static bool io_acct_cancel_pending_work(struct io_wq *wq,
 					struct io_wq_acct *acct,
@@ -284,7 +284,8 @@ static bool io_wq_activate_free_worker(struct io_wq *wq,
  * We need a worker. If we find a free one, we're good. If not, and we're
  * below the max number of workers, create one.
  */
-static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
+static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct,
+				bool fixed)
 {
 	/*
 	 * Most likely an attempt to queue unbounded work on an io_wq that
@@ -302,7 +303,7 @@ static bool io_wq_create_worker(struct io_wq *wq, struct io_wq_acct *acct)
 	raw_spin_unlock(&wq->lock);
 	atomic_inc(&acct->nr_running);
 	atomic_inc(&wq->worker_refs);
-	return create_io_worker(wq, acct->index);
+	return create_io_worker(wq, acct->index, fixed);
 }
 
 static void io_wq_inc_running(struct io_worker *worker)
@@ -312,6 +313,11 @@ static void io_wq_inc_running(struct io_worker *worker)
 	atomic_inc(&acct->nr_running);
 }
 
+static bool is_fixed_worker(struct io_worker *worker)
+{
+	return worker->flags & IO_WORKER_F_FIXED;
+}
+
 static void create_worker_cb(struct callback_head *cb)
 {
 	struct io_worker *worker;
@@ -331,7 +337,7 @@ static void create_worker_cb(struct callback_head *cb)
 	}
 	raw_spin_unlock(&wq->lock);
 	if (do_create) {
-		create_io_worker(wq, worker->create_index);
+		create_io_worker(wq, worker->create_index, is_fixed_worker(worker));
 	} else {
 		atomic_dec(&acct->nr_running);
 		io_worker_ref_put(wq);
@@ -398,6 +404,8 @@ static void io_wq_dec_running(struct io_worker *worker)
 		return;
 	if (!io_acct_run_queue(acct))
 		return;
+	if (is_fixed_worker(worker))
+		return;
 
 	atomic_inc(&acct->nr_running);
 	atomic_inc(&wq->worker_refs);
@@ -601,11 +609,6 @@ static bool is_worker_exiting(struct io_worker *worker)
 	return worker->flags & IO_WORKER_F_EXIT;
 }
 
-static bool is_fixed_worker(struct io_worker *worker)
-{
-	return worker->flags & IO_WORKER_F_FIXED;
-}
-
 static int io_wq_worker(void *data)
 {
 	struct io_worker *worker = data;
@@ -806,7 +809,7 @@ static void io_workqueue_create(struct work_struct *work)
 		kfree(worker);
 }
 
-static bool create_io_worker(struct io_wq *wq, int index)
+static bool create_io_worker(struct io_wq *wq, int index, bool fixed)
 {
 	struct io_wq_acct *acct = &wq->acct[index];
 	struct io_worker *worker;
@@ -833,10 +836,14 @@ static bool create_io_worker(struct io_wq *wq, int index)
 	if (index == IO_WQ_ACCT_BOUND)
 		worker->flags |= IO_WORKER_F_BOUND;
 
+	if (fixed)
+		worker->flags |= IO_WORKER_F_FIXED;
+
 	tsk = create_io_thread(io_wq_worker, worker, NUMA_NO_NODE);
 	if (!IS_ERR(tsk)) {
-		io_init_new_worker(wq, worker, tsk);
-	} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
+		if (!fixed)
+			io_init_new_worker(wq, worker, tsk);
+	} else if (fixed || !io_should_retry_thread(PTR_ERR(tsk))) {
 		kfree(worker);
 		goto fail;
 	} else {
@@ -947,7 +954,7 @@ void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
 	    !atomic_read(&acct->nr_running))) {
 		bool did_create;
 
-		did_create = io_wq_create_worker(wq, acct);
+		did_create = io_wq_create_worker(wq, acct, false);
 		if (likely(did_create))
 			return;
 
-- 
2.25.1