syzbot is hitting __might_sleep() warning [1], for commit 1035b63d3c6fc34a
("n_hdlc: fix read and write locking") changed to set TASK_INTERRUPTIBLE
state before calling copy_to_user(). Let's set TASK_INTERRUPTIBLE state
immediately before calling schedule().[1] https://syzkaller.appspot.com/bug?id=17d5de7f1fcab794cb8c40032f893f52de899324 Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Reported-by: syzbot <syzbot+c244af085a0159d22...@syzkaller.appspotmail.com> Cc: Paul Fulghum <pau...@microgate.com> Cc: Arnd Bergmann <a...@arndb.de> Cc: Alan Cox <a...@lxorguk.ukuu.org.uk> --- drivers/tty/n_hdlc.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c index dabb391..7835489 100644 --- a/drivers/tty/n_hdlc.c +++ b/drivers/tty/n_hdlc.c @@ -589,8 +589,6 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, if (tty_hung_up_p(file)) break; - set_current_state(TASK_INTERRUPTIBLE); - rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); if (rbuf) { if (rbuf->count > nr) { @@ -617,6 +615,7 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, break; } + set_current_state(TASK_INTERRUPTIBLE); schedule(); if (signal_pending(current)) { @@ -673,8 +672,6 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, add_wait_queue(&tty->write_wait, &wait); for (;;) { - set_current_state(TASK_INTERRUPTIBLE); - tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); if (tbuf) break; @@ -683,6 +680,8 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, error = -EAGAIN; break; } + + set_current_state(TASK_INTERRUPTIBLE); schedule(); n_hdlc = tty2n_hdlc (tty); -- 1.8.3.1
