On 12. 04. 24, 5:38, li.ha...@zte.com.cn wrote:
From: Li Hao <li.ha...@zte.com.cn>Cancel the do_wakeup flag in hvc_struct, and change it to immediately wake up tty when hp->n_outbuf is 0 in hvc_push(). When we receive a key input character, the interrupt handling function hvc_handle_interrupt() will be executed, and the echo thread flush_to_ldisc() will be added to the queue. If the user is currently using tcsetattr(), a hang may occur. tcsetattr() enters kernel and waits for hp->n_outbuf to become 0 via tty_wait_until_sent(). If the echo thread finishes executing before reaching tty_wait_until_sent (for example, put_chars() takes too long), it will cause while meeting the wakeup condition (hp->do_wakeup = 1), tty_wait_until_sent() cannot be woken up (missed the tty_wakeup() of this round's tty_poll). Unless the next key input character comes, hvc_poll will be executed, and tty_wakeup() will be performed through the do_wakeup flag. Signed-off-by: Li Hao <li.ha...@zte.com.cn> --- drivers/tty/hvc/hvc_console.c | 12 +++++------- drivers/tty/hvc/hvc_console.h | 1 - 2 files changed, 5 insertions(+), 8 deletions(-) diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c index cd1f657f7..2fa90d938 100644 --- a/drivers/tty/hvc/hvc_console.c +++ b/drivers/tty/hvc/hvc_console.c @@ -476,11 +476,13 @@ static void hvc_hangup(struct tty_struct *tty) static int hvc_push(struct hvc_struct *hp) { int n; + struct tty_struct *tty; n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf); + tty = tty_port_tty_get(&hp->port); if (n <= 0) { if (n == 0 || n == -EAGAIN) { - hp->do_wakeup = 1; + tty_wakeup(tty);
What if tty is NULL? Did you intent to use tty_port_tty_wakeup() instead? thanks, -- js suse labs
