[LinuxPPS] Bug in LinuxPPS startup

[Rodolfo Giometti]

On Mon, Oct 27, 2008 at 11:07:03PM +0000, David wrote:
> 
> The kernel crashes in uart_handle_dcd_change() (inlined into
> check_modem_status()), in the fourth line 
> 
> if (ld->ops->dcd_change)
> 
> I believe ld is returning 0 from tty_ldisc_ref().

This could be true... a possible patch should be:

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index f4cfc66..7cb6b9b 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -492,7 +492,7 @@ uart_handle_dcd_change(struct uart_port *port,
unsigned int 
        struct tty_ldisc *ld = tty_ldisc_ref(info->port.tty);
        struct timespec ts;
 
-       if (ld->ops->dcd_change)
+       if (ld && ld->ops->dcd_change)
 #ifdef CONFIG_PPS_IRQ_EVENTS
                ts = pps_irq_ts[port->irq];
 #else
@@ -512,9 +512,10 @@ uart_handle_dcd_change(struct uart_port *port,
unsigned int
                        tty_hangup(info->port.tty);
        }
 
-       if (ld->ops->dcd_change)
+       if (ld && ld->ops->dcd_change)
                ld->ops->dcd_change(info->port.tty, status, &ts);
-       tty_ldisc_deref(ld);
+       if (ld)
+               tty_ldisc_deref(ld);
 }
 
 /**

Can you please test it?

Ciao,

Rodolfo

-- 

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