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authorThomas Pfaff <tpfaff@pcs.com>2014-04-23 12:33:22 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-04-24 15:38:22 -0700
commit7deb39ed8d9494ea541bcaa69b56036a94f79dc2 (patch)
tree8f7f242c45c98cd06200846e23142b363594cb5a /drivers
parentf94b0572683716f727b25086f8d39671506593ab (diff)
downloadlinux-7deb39ed8d9494ea541bcaa69b56036a94f79dc2.tar.bz2
serial_core: fix uart PORT_UNKNOWN handling
While porting a RS485 driver from 2.6.29 to 3.14, i noticed that the serial tty driver could break it by using uart ports that it does not own : 1. uart_change_pm ist called during uart_open and calls the uart pm function without checking for PORT_UNKNOWN. The fix is to move uart_change_pm from uart_open to uart_port_startup. 2. The return code from the uart request_port call in uart_set_info is not handled properly, leading to the situation that the serial driver also thinks it owns the uart ports. This can triggered by doing following actions : setserial /dev/ttyS0 uart none # release the uart ports modprobe lirc-serial # or any other device that uses the uart setserial /dev/ttyS0 uart 16550 # gives no error and the uart tty driver # can use the ports as well Signed-off-by: Thomas Pfaff <tpfaff@pcs.com> Reviewed-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/serial/serial_core.c39
1 files changed, 21 insertions, 18 deletions
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index f26834d262b3..b68550d95a40 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -137,6 +137,11 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
return 1;
/*
+ * Make sure the device is in D0 state.
+ */
+ uart_change_pm(state, UART_PM_STATE_ON);
+
+ /*
* Initialise and allocate the transmit and temporary
* buffer.
*/
@@ -825,25 +830,29 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
* If we fail to request resources for the
* new port, try to restore the old settings.
*/
- if (retval && old_type != PORT_UNKNOWN) {
+ if (retval) {
uport->iobase = old_iobase;
uport->type = old_type;
uport->hub6 = old_hub6;
uport->iotype = old_iotype;
uport->regshift = old_shift;
uport->mapbase = old_mapbase;
- retval = uport->ops->request_port(uport);
- /*
- * If we failed to restore the old settings,
- * we fail like this.
- */
- if (retval)
- uport->type = PORT_UNKNOWN;
- /*
- * We failed anyway.
- */
- retval = -EBUSY;
+ if (old_type != PORT_UNKNOWN) {
+ retval = uport->ops->request_port(uport);
+ /*
+ * If we failed to restore the old settings,
+ * we fail like this.
+ */
+ if (retval)
+ uport->type = PORT_UNKNOWN;
+
+ /*
+ * We failed anyway.
+ */
+ retval = -EBUSY;
+ }
+
/* Added to return the correct error -Ram Gupta */
goto exit;
}
@@ -1571,12 +1580,6 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
}
/*
- * Make sure the device is in D0 state.
- */
- if (port->count == 1)
- uart_change_pm(state, UART_PM_STATE_ON);
-
- /*
* Start up the serial port.
*/
retval = uart_startup(tty, state, 0);