linux-kernel - Re: [alternative-merged] serial-apbuartc-fix-two-problems-related-to-grlib_apbuart

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Date:	Thu, 20 May 2010 21:52:36 +0200
From:	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:	Greg KH <greg@...ah.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	kristoffer@...sler.com, Andrew Morton <akpm@...ux-foundation.org>,
	davem@...emloft.net, Anton Vorontsov <avorontsov@...mvista.com>
Subject: Re: [alternative-merged]
 serial-apbuartc-fix-two-problems-related-to-grlib_apbuart_configure.patch
 removed from -mm tree

Hi,

I found two problems using the Simics' sunfire target. It occurs as well on real machines.

1. At grlib_apbuart_configure() in apbuart.c, prop can be NULL if
"clock-frequency" doesn't exist in the OF tree:

       /* Get bus frequency */
       rp = of_find_node_by_path("/");
       rp = of_get_next_child(rp, NULL);
       prop = of_get_property(rp, "clock-frequency", NULL);
       freq_khz = *prop;

2. In addition, apbuart.c does not check if there aren't any ports
configured after calls to grlib_apbuart_configure(), so other oops will
occur if no port was configured (e.g. uart_set_options() because of
port->ops).

In order to solve that, I added a check after both of the calls to
grlib_apbuart_configure().

The patch that I provide below prevents both problems in the Simics'
sunfire target. In addition, it warns the users if no ports were found.

Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Acked-by: Kristoffer Glembo <kristoffer@...sler.com>
---
--- drivers/serial/apbuart.c.orig	2010-04-26 16:48:30.000000000 +0200
+++ drivers/serial/apbuart.c	2010-05-11 15:21:28.984666230 +0200
@@ -525,6 +525,9 @@ static void grlib_apbuart_configure(void
 static int __init apbuart_console_init(void)
 {
 	grlib_apbuart_configure();
+	if (grlib_apbuart_port_nr == 0)
+		return 0;
+
 	register_console(&grlib_apbuart_console);
 	return 0;
 }
@@ -612,6 +615,10 @@ static void grlib_apbuart_configure(void
 	rp = of_find_node_by_path("/");
 	rp = of_get_next_child(rp, NULL);
 	prop = of_get_property(rp, "clock-frequency", NULL);
+	if (prop == NULL) {
+		grlib_apbuart_port_nr = 0;
+		return;
+	}
 	freq_khz = *prop;
 
 	line = 0;
@@ -666,6 +673,10 @@ static int __init grlib_apbuart_init(voi
 
 	/* Find all APBUARTS in device the tree and initialize their ports */
 	grlib_apbuart_configure();
+	if (grlib_apbuart_port_nr == 0) {
+		printk(KERN_INFO "Serial: GRLIB APBUART: No ports found.\n");
+		return -ENODEV;
+	}
 
 	printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
 


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