From d033e82db9a5e9bc93224c8a058b9c03e4e3f8ad Mon Sep 17 00:00:00 2001 From: Leilei Zhao Date: Thu, 9 Apr 2015 10:48:15 +0800 Subject: [PATCH] tty/serial: at91: handle IRQ status more safely Handle the changed flag of IRQ status in interruption instead of handling it in tasklet due to the tasklet may be scheduled more than once in one interruption. Otherwise, the changed status may be processed more than once which will lead to unexpected result. And seriously, kernel will crash. Signed-off-by: Leilei Zhao Acked-by: Nicolas Ferre Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 27dade29646b..b1fcddd6652a 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -165,6 +165,7 @@ struct atmel_uart_port { struct tasklet_struct tasklet; unsigned int irq_status; unsigned int irq_status_prev; + unsigned int status_change; struct circ_buf rx_ring; @@ -1177,6 +1178,9 @@ atmel_handle_status(struct uart_port *port, unsigned int pending, if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC | ATMEL_US_CTSIC)) { atmel_port->irq_status = status; + atmel_port->status_change = atmel_port->irq_status ^ + atmel_port->irq_status_prev; + atmel_port->irq_status_prev = status; tasklet_schedule(&atmel_port->tasklet); } } @@ -1523,17 +1527,14 @@ static void atmel_tasklet_func(unsigned long data) { struct uart_port *port = (struct uart_port *)data; struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); - unsigned int status; - unsigned int status_change; + unsigned int status = atmel_port->irq_status; + unsigned int status_change = atmel_port->status_change; /* The interrupt handler does not take the lock */ spin_lock(&port->lock); atmel_port->schedule_tx(port); - status = atmel_port->irq_status; - status_change = status ^ atmel_port->irq_status_prev; - if (status_change & (ATMEL_US_RI | ATMEL_US_DSR | ATMEL_US_DCD | ATMEL_US_CTS)) { /* TODO: All reads to CSR will clear these interrupts! */ @@ -1548,7 +1549,7 @@ static void atmel_tasklet_func(unsigned long data) wake_up_interruptible(&port->state->port.delta_msr_wait); - atmel_port->irq_status_prev = status; + atmel_port->status_change = 0; } atmel_port->schedule_rx(port); -- 2.39.5