From: Jiri Slaby <jslaby@suse.cz> stable inclusion from stable-v5.10.111 commit 3309b322171180828564c386443eb5a62eabc862 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5GL1Z Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 988c7c00691008ea1daaa1235680a0da49dab4e8 ] The commit c15c3747ee32 (serial: samsung: fix potential soft lockup during uart write) added an unlock of port->lock before uart_write_wakeup() and a lock after it. It was always problematic to write data from tty_ldisc_ops::write_wakeup and it was even documented that way. We fixed the line disciplines to conform to this recently. So if there is still a missed one, we should fix them instead of this workaround. On the top of that, s3c24xx_serial_tx_dma_complete() in this driver still holds the port->lock while calling uart_write_wakeup(). So revert the wrap added by the commit above. Cc: Thomas Abraham <thomas.abraham@linaro.org> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Hyeonkook Kim <hk619.kim@samsung.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> Link: https://lore.kernel.org/r/20220308115153.4225-1-jslaby@suse.cz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- drivers/tty/serial/samsung_tty.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c index 8ae3e03fbd8c..81faead3c4f8 100644 --- a/drivers/tty/serial/samsung_tty.c +++ b/drivers/tty/serial/samsung_tty.c @@ -883,11 +883,8 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id) goto out; } - if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) { - spin_unlock(&port->lock); + if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) uart_write_wakeup(port); - spin_lock(&port->lock); - } if (uart_circ_empty(xmit)) s3c24xx_serial_stop_tx(port); -- 2.20.1