diff options
authorAkira Takeuchi <>2008-12-10 12:43:24 +0000
committerLinus Torvalds <>2008-12-10 13:34:33 -0800
commita8893fb3e61473349b052794ae157b938e3b2b98 (patch)
parentcb32898c0996e78509a4b21b068209eb2d569f00 (diff)
MN10300: Discard low-priority Tx interrupts when closing an on-chip serial port
Discard low-prioriy Tx interrupts when closing an MN10300 on-chip serial port. The MN10300 on-chip serial port uses three interrupts to manage its serial ports: (1) A very high priority interrupt that drives virtual DMA for Rx. (2) A very high priority interrupt that drives virtual DMA for Tx. (3) A normal priority virtual interrupt that does the normal UART interrupt stuff and is shared between Rx and Tx. mn10300_serial_stop_tx() only disables the high priority Tx interrupt. It doesn't also disable the normal priority one because it is shared with Rx. However, the high priority interrupt may interrupt local_irq_disabled() sections, and so may have queued up a low priority virtual interrupt whilst the UART driver is asking for the Tx interrupt to be disabled. The result of this can be an oops when we try to process the interrupt in mn10300_serial_transmit_interrupt() as port-> and port->>tty may have gone away. To deal with this, if either of those pointers is NULL, we make sure the high-priority Tx interrupt is disabled and discard the interrupt. The low priority interrupt is disabled by the mn10300_serial_pic irq_chip table. Signed-off-by: Akira Takeuchi <> Signed-off-by: David Howells <> Signed-off-by: Linus Torvalds <>
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/mn10300-serial.c b/arch/mn10300/kernel/mn10300-serial.c
index aa07d0cd1905..59b9c4bf9583 100644
--- a/arch/mn10300/kernel/mn10300-serial.c
+++ b/arch/mn10300/kernel/mn10300-serial.c
@@ -566,6 +566,11 @@ static void mn10300_serial_transmit_interrupt(struct mn10300_serial_port *port)
_enter("%s", port->name);
+ if (!port-> || !port->>port.tty) {
+ mn10300_serial_dis_tx_intr(port);
+ return;
+ }
if (uart_tx_stopped(&port->uart) ||