On 2021/10/26 下午10:47, Jens Axboe wrote:
On 10/26/21 4:32 AM, Muchun Song wrote:
On Tue, Oct 26, 2021 at 11:23 AM Zqiang <qiang.zhang1211@xxxxxxxxx> wrote:
Due to raw_spin_lock/unlock() contains preempt_disable/enable() action,
already regarded as RCU critical region, so remove unnecessary
rcu_read_lock/unlock().
Signed-off-by: Zqiang <qiang.zhang1211@xxxxxxxxx>
---
fs/io-wq.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/fs/io-wq.c b/fs/io-wq.c
index cd88602e2e81..401be005d089 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -855,9 +855,7 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
io_wqe_insert_work(wqe, work);
clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
- rcu_read_lock();
Add a comment like:
/* spin_lock can serve as an RCU read-side critical section. */
Note that it's a raw spinlock. Honestly I'd probably prefer if we just leave
it as-is. There are plans to improve the io-wq locking, and a rcu lock/unlock
is pretty cheap.
That said, if resend with a comment fully detailing why it's OK currently,
then I'd be fine with that as well.
Thanks Jens Axboe, Muchun
I will add a comment fully detailing and resend.
