The uart_handle_cts_change() function in serial_core expects the caller
to hold uport->lock. For example, I have seen the below kernel splat,
when the Bluetooth driver is loaded on an i.MX28 board.
[ 85.119255] ------------[ cut here ]------------
[ 85.124413] WARNING: CPU: 0 PID: 27 at /drivers/tty/serial/serial_core.c:3453 uart_handle_cts_change+0xb4/0xec
[ 85.134694] Modules linked in: hci_uart bluetooth ecdh_generic ecc wlcore_sdio configfs
[ 85.143314] CPU: 0 PID: 27 Comm: kworker/u3:0 Not tainted 6.6.3-00021-gd62a2f068f92 #1
[ 85.151396] Hardware name: Freescale MXS (Device Tree)
[ 85.156679] Workqueue: hci0 hci_power_on [bluetooth]
[ 85.164243] unwind_backtrace from show_stack+0x10/0x14
(...)
Signed-off-by: Emil Kronborg <emil.kronborg@xxxxxxxxxxxxxx>
---
drivers/tty/serial/mxs-auart.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 4749331fe618..1e8853eae504 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1086,11 +1086,13 @@ static void mxs_auart_set_ldisc(struct uart_port *port,
static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
{
- u32 istat;
+ u32 istat, stat;
struct mxs_auart_port *s = context;
u32 mctrl_temp = s->mctrl_prev;
- u32 stat = mxs_read(s, REG_STAT);
+ uart_port_lock(&s->port);
+
+ stat = mxs_read(s, REG_STAT);
istat = mxs_read(s, REG_INTR);
/* ack irq */
@@ -1126,6 +1128,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
istat &= ~AUART_INTR_TXIS;
}
+ uart_port_unlock(&s->port);
+
return IRQ_HANDLED;
}
--
2.44.0
