| Message ID | d775ae2d-a2ac-439e-8e2b-134749f60f30@I-love.SAKURA.ne.jp |
|---|---|
| State | New |
| Headers | show |
| Series | serial: drop debugging WARN_ON_ONCE() from uart_write() | expand |
On 28. 05. 24, 17:05, Tetsuo Handa wrote: > syzbot is reporting lockdep warning upon > > int disc = 7; > ioctl(open("/dev/ttyS3", O_RDONLY), TIOCSETD, &disc); > > sequence. Do like what commit 5f1149d2f4bf ("serial: drop debugging > WARN_ON_ONCE() from uart_put_char()") does. > > Reported-by: syzbot+f78380e4eae53c64125c@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=f78380e4eae53c64125c > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Ugh, definitely: Acked-by: Jiri Slaby <jirislaby@kernel.org> > --- > Example is https://syzkaller.appspot.com/text?tag=CrashReport&x=100271ec980000 . > But not using this example, for this link will disappear eventually. > > By the way, do we want to also guard uart_port_lock'ed section using > printk_deferred_enter()/printk_deferred_exit(), for trying to use e.g. > WARN_ON() inside such section will result in the same lockdep warning? At this point, I don't know the answer. > --- a/drivers/tty/serial/serial_core.c > +++ b/drivers/tty/serial/serial_core.c > @@ -622,7 +622,7 @@ static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count) > return -EL3HLT; > > port = uart_port_lock(state, flags); > - if (WARN_ON_ONCE(!state->port.xmit_buf)) { > + if (!state->port.xmit_buf) { > uart_port_unlock(port, flags); > return 0; > }
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 2c1a0254d3f4..0c4d60976663 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -622,7 +622,7 @@ static ssize_t uart_write(struct tty_struct *tty, const u8 *buf, size_t count) return -EL3HLT; port = uart_port_lock(state, flags); - if (WARN_ON_ONCE(!state->port.xmit_buf)) { + if (!state->port.xmit_buf) { uart_port_unlock(port, flags); return 0; }
syzbot is reporting lockdep warning upon int disc = 7; ioctl(open("/dev/ttyS3", O_RDONLY), TIOCSETD, &disc); sequence. Do like what commit 5f1149d2f4bf ("serial: drop debugging WARN_ON_ONCE() from uart_put_char()") does. Reported-by: syzbot+f78380e4eae53c64125c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f78380e4eae53c64125c Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> --- Example is https://syzkaller.appspot.com/text?tag=CrashReport&x=100271ec980000 . But not using this example, for this link will disappear eventually. By the way, do we want to also guard uart_port_lock'ed section using printk_deferred_enter()/printk_deferred_exit(), for trying to use e.g. WARN_ON() inside such section will result in the same lockdep warning? drivers/tty/serial/serial_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)