[PATCH 5.14 201/432] tty: serial: jsm: hold port lock when reporting modem line changes

Greg Kroah-Hartman
2021-09-16T17:34:12Z

From: Zheyu Ma <zheyuma97@gmail.com>

[ Upstream commit 240e126c28df084222f0b661321e8e3ecb0d232e ]

uart_handle_dcd_change() requires a port lock to be held and will emit a
warning when lockdep is enabled.

Held corresponding lock to fix the following warnings.

[ 132.528648] WARNING: CPU: 5 PID: 11600 at drivers/tty/serial/serial_core.c:3046 uart_handle_dcd_change+0xf4/0x120
[ 132.530482] Modules linked in:
[ 132.531050] CPU: 5 PID: 11600 Comm: jsm Not tainted 5.14.0-rc1-00003-g7fef2edf7cc7-dirty #31
[ 132.535268] RIP: 0010:uart_handle_dcd_change+0xf4/0x120
[ 132.557100] Call Trace:
[ 132.557562] ? __free_pages+0x83/0xb0
[ 132.558213] neo_parse_modem+0x156/0x220
[ 132.558897] neo_param+0x399/0x840
[ 132.559495] jsm_tty_open+0x12f/0x2d0
[ 132.560131] uart_startup.part.18+0x153/0x340
[ 132.560888] ? lock_is_held_type+0xe9/0x140
[ 132.561660] uart_port_activate+0x7f/0xe0
[ 132.562351] ? uart_startup.part.18+0x340/0x340
[ 132.563003] tty_port_open+0x8d/0xf0
[ 132.563523] ? uart_set_options+0x1e0/0x1e0
[ 132.564125] uart_open+0x24/0x40
[ 132.564604] tty_open+0x15c/0x630

Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Link: https://lore.kernel.org/r/1626242003-3809-1-git-send-email-zheyuma97@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/jsm/jsm_neo.c | 2 ++
drivers/tty/serial/jsm/jsm_tty.c | 3 +++
2 files changed, 5 insertions(+)

diff --git a/drivers/tty/serial/jsm/jsm_neo.c b/drivers/tty/serial/jsm/jsm_neo.c
index bf0e2a4cb0ce..c6f927a76c3b 100644
--- a/drivers/tty/serial/jsm/jsm_neo.c
+++ b/drivers/tty/serial/jsm/jsm_neo.c
@@ -815,7 +815,9 @@ static void neo_parse_isr(struct jsm_board *brd, u32 port)
/* Parse any modem signal changes */
jsm_dbg(INTR, &ch->ch_bd->pci_dev,
"MOD_STAT: sending to parse_modem_sigs\n");
+ spin_lock_irqsave(&ch->uart_port.lock, lock_flags);
neo_parse_modem(ch, readb(&ch->ch_neo_uart->msr));
+ spin_unlock_irqrestore(&ch->uart_port.lock, lock_flags);
}
}

diff --git a/drivers/tty/serial/jsm/jsm_tty.c b/drivers/tty/serial/jsm/jsm_tty.c
index 8e42a7682c63..d74cbbbf33c6 100644
--- a/drivers/tty/serial/jsm/jsm_tty.c
+++ b/drivers/tty/serial/jsm/jsm_tty.c
@@ -187,6 +187,7 @@ static void jsm_tty_break(struct uart_port *port, int break_state)

static int jsm_tty_open(struct uart_port *port)
{
+ unsigned long lock_flags;
struct jsm_board *brd;
struct jsm_channel *channel =
container_of(port, struct jsm_channel, uart_port);
@@ -240,6 +241,7 @@ static int jsm_tty_open(struct uart_port *port)
channel->ch_cached_lsr = 0;
channel->ch_stops_sent = 0;

+ spin_lock_irqsave(&port->lock, lock_flags);
termios = &port->state->port.tty->termios;
channel->ch_c_cflag = termios->c_cflag;
channel->ch_c_iflag = termios->c_iflag;
@@ -259,6 +261,7 @@ static int jsm_tty_open(struct uart_port *port)
jsm_carrier(channel);

channel->ch_open_count++;
+ spin_unlock_irqrestore(&port->lock, lock_flags);

jsm_dbg(OPEN, &channel->ch_bd->pci_dev, "finish\n");
return 0;
--
2.30.2