| Message ID | 20240416071904.21440-1-jirislaby@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | serial: drop debugging WARN_ON_ONCE() from uart_put_char() | expand |
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 558f159ada15..bd4a72f8e821 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -573,7 +573,7 @@ static int uart_put_char(struct tty_struct *tty, u8 c) int ret = 0; 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; }
Pengfei Xu reports, that the -next commit 1788cf6a91d9 (tty: serial: switch from circ_buf to kfifo) tries to emit a WARNING and that leads to lockdep errors. Obviously we cannot print anything from uart_put_char()! This WARN_ON_ONCE() was/is a debug aid to check if the condition in uart_put_char() can happen at all. Pengfei Xu confirmed it can. Unlike me and kbuild bot in my queue. Second, I completely forgot about it, so I did not remove it in the final version, nor mentioned it in the commit log. Drop it now as we are all good. And we even have stack traces (and a reproducer)! Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> Reported-by: Pengfei Xu <pengfei.xu@intel.com> --- drivers/tty/serial/serial_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)