From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 9 Aug 2023 18:58:59 +0000 (-0600)
Subject: io_uring/io-wq: don't grab wq->lock for worker activation
X-Git-Tag: v6.6-rc1~152^2~26
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=78848b9b05623cfddb790d23b0dc38a275eb0763;p=thirdparty%2Flinux.git

io_uring/io-wq: don't grab wq->lock for worker activation

The worker free list is RCU protected, and checks for workers going away
when iterating it. There's no need to hold the wq->lock around the
lookup.

Reviewed-by: Hao Xu <howeyxu@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index 399e9a15c38d6..3e7025b9e0dd5 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -909,13 +909,10 @@ void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
 	clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
 	raw_spin_unlock(&acct->lock);
 
-	raw_spin_lock(&wq->lock);
 	rcu_read_lock();
 	do_create = !io_wq_activate_free_worker(wq, acct);
 	rcu_read_unlock();
 
-	raw_spin_unlock(&wq->lock);
-
 	if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
 	    !atomic_read(&acct->nr_running))) {
 		bool did_create;