linux-kernel - [PATCH 6/9] io-wq: fixed worker exit

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Date:   Fri, 29 Apr 2022 18:18:55 +0800
From:   Hao Xu <haoxu.linux@...il.com>
To:     io-uring@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 6/9] io-wq: fixed worker exit

From: Hao Xu <howeyxu@...cent.com>

Implement the fixed worker exit

Signed-off-by: Hao Xu <howeyxu@...cent.com>
---
 fs/io-wq.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/fs/io-wq.c b/fs/io-wq.c
index a1a10fb204a7..2feff19970ca 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -259,6 +259,29 @@ static bool io_task_worker_match(struct callback_head *cb, void *data)
 	return worker == data;
 }
 
+static void io_fixed_worker_exit(struct io_worker *worker)
+{
+	int *nr_fixed;
+	int index = worker->acct.index;
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wqe_acct *acct = io_get_acct(wqe, index == 0, true);
+	struct io_worker **fixed_workers;
+
+	raw_spin_lock(&acct->lock);
+	fixed_workers = acct->fixed_workers;
+	if (!fixed_workers || worker->index == -1) {
+		raw_spin_unlock(&acct->lock);
+		return;
+	}
+	nr_fixed = &acct->nr_fixed;
+	/* reuse variable index to represent fixed worker index in its array */
+	index = worker->index;
+	fixed_workers[index] = fixed_workers[*nr_fixed - 1];
+	(*nr_fixed)--;
+	fixed_workers[index]->index = index;
+	raw_spin_unlock(&acct->lock);
+}
+
 static void io_worker_exit(struct io_worker *worker)
 {
 	struct io_wqe *wqe = worker->wqe;
@@ -682,6 +705,7 @@ static int io_wqe_worker(void *data)
 	struct io_wqe *wqe = worker->wqe;
 	struct io_wq *wq = wqe->wq;
 	bool last_timeout = false;
+	bool fixed = worker->flags & IO_WORKER_F_FIXED;
 	char buf[TASK_COMM_LEN];
 
 	worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
@@ -732,6 +756,8 @@ static int io_wqe_worker(void *data)
 
 	if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
 		io_worker_handle_work(worker);
+	if (fixed)
+		io_fixed_worker_exit(worker);
 
 	audit_free(current);
 	io_worker_exit(worker);
-- 
2.36.0