linux-kernel - Re: [PATCH] [OOPS] apbuart.c: Two problems related to grlib_apbuart

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Message-ID: <AANLkTikatJDpPHw8WeE7XwLVgeg4A1Atd2ARoJxomzzl@mail.gmail.com>
Date:	Mon, 10 May 2010 15:20:48 +0200
From:	Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>, kristoffer@...sler.com
Cc:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] [OOPS] apbuart.c: Two problems related to 
	grlib_apbuart_configure()

On Sat, May 8, 2010 at 11:58 PM, Miguel Ojeda
<miguel.ojeda.sandonis@...il.com> wrote:
> Hi,
>
> I found two problems using the Simics' sunfire target, so maybe the
> following does not occur in 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.
>
> Tested against 2.6.33.3. Please review.
>
> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
> ---
> --- drivers/serial/apbuart.c.orig       2010-04-26 16:48:30.000000000 +0200
> +++ drivers/serial/apbuart.c    2010-05-08 23:50:36.786148571 +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 +615,8 @@ 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; should be added here or in apbuart.h better.

> +               return;
>        freq_khz = *prop;
>
>        line = 0;
> @@ -666,6 +671,11 @@ 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",
> +                       __FILE__);
> +               return 0;
> +       }
>
>        printk(KERN_INFO "Serial: GRLIB APBUART driver\n");
>
>
>
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