[PATCH 6.1 290/473] serial: max3100: Lock port->lock when calling uart_handle_cts_change()

Greg Kroah-Hartman
2024-06-06T14:16:46Z

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

[ Upstream commit 77ab53371a2066fdf9b895246505f5ef5a4b5d47 ]

uart_handle_cts_change() has to be called with port lock taken,
Since we run it in a separate work, the lock may not be taken at
the time of running. Make sure that it's taken by explicitly doing
that. Without it we got a splat:

WARNING: CPU: 0 PID: 10 at drivers/tty/serial/serial_core.c:3491 uart_handle_cts_change+0xa6/0xb0
...
Workqueue: max3100-0 max3100_work [max3100]
RIP: 0010:uart_handle_cts_change+0xa6/0xb0
...
max3100_handlerx+0xc5/0x110 [max3100]
max3100_work+0x12a/0x340 [max3100]

Fixes: 7831d56b0a35 ("tty: MAX3100")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240402195306.269276-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/max3100.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
index c69602f356fdc..1c4a2b1b1f690 100644
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -213,7 +213,7 @@ static int max3100_sr(struct max3100_port *s, u16 tx, u16 *rx)
return 0;
}

-static int max3100_handlerx(struct max3100_port *s, u16 rx)
+static int max3100_handlerx_unlocked(struct max3100_port *s, u16 rx)
{
unsigned int ch, flg, status = 0;
int ret = 0, cts;
@@ -253,6 +253,17 @@ static int max3100_handlerx(struct max3100_port *s, u16 rx)
return ret;
}

+static int max3100_handlerx(struct max3100_port *s, u16 rx)
+{
+ unsigned long flags;
+ int ret;
+
+ uart_port_lock_irqsave(&s->port, &flags);
+ ret = max3100_handlerx_unlocked(s, rx);
+ uart_port_unlock_irqrestore(&s->port, flags);
+ return ret;
+}
+
static void max3100_work(struct work_struct *w)
{
struct max3100_port *s = container_of(w, struct max3100_port, work);
--
2.43.0