> -----邮件原件----- > 发件人: Kohli, Gaurav [mailto:gko...@codeaurora.org] > 发送时间: 2019年1月11日 21:57 > 收件人: Li,Rongqing <lirongq...@baidu.com>; linux-kernel@vger.kernel.org; > jsl...@suse.com; gre...@linuxfoundation.org; a...@linux.intel.com > 主题: Re: [PATCH][v2] tty: fix race between flush_to_ldisc and tty_open > > Hi, > > it don't seems to be good idea to put lock on one function and unlock in some > other function. If in future some one has to call tty_init_dev, how he can > track > the unlocking as well of ldisc lock. > > Regards > Gaurav >
This similar condition has existed for a long time, tty_unlock(tty) must be called in some other functions who call tty_init_dev, since tty_init_dev hold tty_lock, and does not release it so I think it is user responsibility to fully understand tty_init_dev; and I can add some comments for tty_init_dev if this patch can be acceptable; or a workaround like below: diff --git a/drivers/tty/tty_buffer.c b/drivers/tty/tty_buffer.c index a42a028a9d4e..2f5ad256b6ad 100644 --- a/drivers/tty/tty_buffer.c +++ b/drivers/tty/tty_buffer.c @@ -425,7 +425,7 @@ static void flush_to_ldisc(struct work_struct *work) struct tty_ldisc *disc; tty = port->itty; - if (tty == NULL) + if (tty == NULL || tty->driver_data == NULL) return; disc = tty_ldisc_ref(tty); thanks -RongQing