On Wed, Jul 04, 2007 at 04:38:24PM +0530, Satyam Sharma wrote:
>  struct netconsole_target {
>       struct list_head        list;
> +     struct config_item      item;
> +     int                     id;
> +     int                     enabled;
>       int                     dev_status;
>       struct netpoll          np;
>  };

        If you're trying to be good with your CONFIG_NETCONSOLE_DYNAMIC
ifdefs, you probably want to ifdef the item.  You'll save space when
NETCONSOLE_DYNAMIC is off.

> +#ifdef       CONFIG_NETCONSOLE_DYNAMIC
> +
> +/*
> + * Targets that were created by parsing the boot/module option string
> + * do not exist in the configfs hierarchy and will never go away (and
> + * have zeroed-out config_item members). So make these a no-op for them.
> + */
> +static void netconsole_target_get(struct netconsole_target *nt)
> +{
> +     static struct config_item empty_item;   /* Zeroed-out config_item */
> +
> +     if (memcmp(&nt->item, &empty_item, sizeof(struct config_item)))
> +             config_item_get(&nt->item);
> +}

        I was going to point out that you could merely check
config_item_name(&nt->item) != NULL, because a valid configfs object has
a name and your zeroed object does not.  But your followup email
suggests you'll be removing this code anyway.
        I don't, off the top of my head, see a problem with removing the
_get/_put cycle, because you do have them under the spinlock.  Things
should behave correctly.  However, the _get/_put pair is "cleaner", in
that it expresses the relationship and doesn't add a special case of "I
happen to know this is safe".

> + * Our subsystem hierarchy is:
> + *
> + * /config/netconsole/
> + *                |
> + *                <target>/
> + *                |       id
> + *                |       enabled

        Your configfs bits seem to be pretty straightforward.

> +             /*
> +              * Skip netpoll_parse_options() -- all the attributes are
> +              * already configured in nt->np through configfs. But at
> +              * least let's print the useful stuff it used to output :-)
> +              */
> +             printk(KERN_INFO "%s: local port %d\n",
> +                              np->name, np->local_port);
> +             printk(KERN_INFO "%s: local IP %d.%d.%d.%d\n",
> +                              np->name, HIPQUAD(np->local_ip));
> +             printk(KERN_INFO "%s: interface %s\n",
> +                              np->name, np->dev_name);
> +             printk(KERN_INFO "%s: remote port %d\n",
> +                              np->name, np->remote_port);
> +             printk(KERN_INFO "%s: remote IP %d.%d.%d.%d\n",
> +                              np->name, HIPQUAD(np->remote_ip));
> +             printk(KERN_INFO "%s: remote ethernet address "
> +                              "%02x:%02x:%02x:%02x:%02x:%02x\n",
> +                              np->name,
> +                              np->remote_mac[0], np->remote_mac[1],
> +                              np->remote_mac[2], np->remote_mac[3],
> +                              np->remote_mac[4], np->remote_mac[5]);

        Shouldn't you break this out into a function so that both places
can use it?

> +#define NETCONSOLE_TARGET_ATTR_RO(_name)                             \
> +static struct netconsole_target_attr netconsole_target_##_name =     \
> +__CONFIGFS_ATTR(_name, S_IRUGO, show_##_name, NULL)
> +
> +#define NETCONSOLE_TARGET_ATTR_RW(_name)                             \
> +static struct netconsole_target_attr netconsole_target_##_name =     \
> +__CONFIGFS_ATTR(_name, S_IRUGO | S_IWUSR, show_##_name, store_##_name)

        Perhaps an indent would be clearer, but that's a tiny nitpick.

>       /*
> -      * Neither the netdev notifier, nor the console have been
> -      * registered so far. Nobody's racing us, so skip the lock.
> +      * Neither the netdev notifier, not the configfs subsystem and
> +      * nor the console have been registered so far. Nobody's racing us,
> +      * so skip the lock.

        Once again, while you know you can skip the lock, it's unclear
without the comment.  Perhaps using the lock makes it explicitly
"correct"?  Food for thought.

> @@ -251,6 +796,17 @@ static int __init init_netconsole(void)
>       if (err)
>               goto fail;
>  
> +#ifdef       CONFIG_NETCONSOLE_DYNAMIC
> +     config_group_init(&netconsole_subsys.su_group);
> +     mutex_init(&netconsole_subsys.su_mtx);
> +
> +     err = configfs_register_subsystem(&netconsole_subsys);
> +     if (err) {
> +             unregister_netdevice_notifier(&netconsole_netdev_notifier);
> +             goto fail;
> +     }
> +#endif       /* CONFIG_NETCONSOLE_DYNAMIC */

        I'd abstract this to a dynamic_init() function.

> +
> +#ifdef       CONFIG_NETCONSOLE_DYNAMIC
> +     configfs_unregister_subsystem(&netconsole_subsys);
> +#endif       /* CONFIG_NETCONSOLE_DYNAMIC */
> +

        and this to an dynamic_fini() function.  Basically, do what you
did with _get()/_put().  This keeps the ifdef up above and out of the
functions themselves.

#ifdef CONFIG_NETCONSOLE_DYNAMIC
static int __init dynamic_netconsole_init(void)
{
        config_group_init(&netconsole_subsys.su_group);
        mutex_init(&netconsole_subsys.su_mtx);
        return configfs_register_subsystem(&netconsole_subsys);
}
#else
static int __init dynamic_netconsole_init(void)
{
        return 0;
}
#endif   


Joel

-- 

Life's Little Instruction Book #3

        "Watch a sunrise at least once a year."

Joel Becker
Principal Software Developer
Oracle
E-mail: [EMAIL PROTECTED]
Phone: (650) 506-8127
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