Fix panic caused by a race between men_z135_intr() and men_z135_set_termios().
men_z135_intr() and men_z135_set_termios() both hold the struct uart_port::lock
spinlock, but men_z135_intr() does a spin_lock_irqsave() and
men_z135_set_termios() does a normal spin_lock(), which can lead to a deadlock
when an interrupt is called while the lock is being helt by
men_z135_set_termios().
This was discovered using a insmod, hardware looppback send/receive, rmmod
stress test.
Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: Andreas Werner <andreas.werner@xxxxxx>
---
drivers/tty/serial/men_z135_uart.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/men_z135_uart.c b/drivers/tty/serial/men_z135_uart.c
index 35c5550..d020435 100644
--- a/drivers/tty/serial/men_z135_uart.c
+++ b/drivers/tty/serial/men_z135_uart.c
@@ -656,6 +656,7 @@ static void men_z135_set_termios(struct uart_port *port,
struct ktermios *old)
{
struct men_z135_port *uart = to_men_z135(port);
+ unsigned long flags;
unsigned int baud;
u32 conf_reg;
u32 bd_reg;
@@ -717,7 +718,7 @@ static void men_z135_set_termios(struct uart_port *port,
baud = uart_get_baud_rate(port, termios, old, 0, uart_freq / 16);
- spin_lock(&port->lock);
+ spin_lock_irqsave(&port->lock, flags);
if (tty_termios_baud_rate(termios))
tty_termios_encode_baud_rate(termios, baud, baud);
@@ -725,7 +726,7 @@ static void men_z135_set_termios(struct uart_port *port,
iowrite32(bd_reg, port->membase + MEN_Z135_BAUD_REG);
uart_update_timeout(port, termios->c_cflag, baud);
- spin_unlock(&port->lock);
+ spin_unlock_irqrestore(&port->lock, flags);
}
static const char *men_z135_type(struct uart_port *port)
--
2.4.3
--
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