From ae01e52da244af5d650378ada1bfd2d946dc1b45 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Wed, 29 May 2024 00:05:53 +0900
Subject: [PATCH] serial: drop debugging WARN_ON_ONCE() from uart_write()
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>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/d775ae2d-a2ac-439e-8e2b-134749f60f30@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2c1a0254d3f4a..0c4d609766633 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;
}
--
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