netconsole: avoid CON_ENABLED misuse to track registration

The CON_ENABLED flag is being misused to track whether or not the
extended console should be or has been registered. Instead use
a local variable to decide if the extended console should be
registered and console_is_registered() to determine if it has
been registered.

Also add a check in cleanup_netconsole() to only unregister the
extended console if it has been registered.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-32-john.ogness@linutronix.de

diff --git a/drivers/net/netconsole.c b/drivers/net/netconsole.c
index bdff9ac..4f4f795 100644 (file)
--- a/drivers/net/netconsole.c
+++ b/drivers/net/netconsole.c
@@ -332,10 +332,8 @@ static ssize_t enabled_store(struct config_item *item,
        }
 
        if (enabled) {  /* true */
-               if (nt->extended && !(netconsole_ext.flags & CON_ENABLED)) {
-                       netconsole_ext.flags |= CON_ENABLED;
+               if (nt->extended && !console_is_registered(&netconsole_ext))
                        register_console(&netconsole_ext);
-               }
 
                /*
                 * Skip netpoll_parse_options() -- all the attributes are
@@ -869,7 +867,7 @@ static void write_msg(struct console *con, const char *msg, unsigned int len)
 
 static struct console netconsole_ext = {
        .name   = "netcon_ext",
-       .flags  = CON_EXTENDED, /* starts disabled, registered on first use */
+       .flags  = CON_ENABLED | CON_EXTENDED,
        .write  = write_ext_msg,
 };
 
@@ -883,6 +881,7 @@ static int __init init_netconsole(void)
 {
        int err;
        struct netconsole_target *nt, *tmp;
+       bool extended = false;
        unsigned long flags;
        char *target_config;
        char *input = config;
@@ -895,11 +894,12 @@ static int __init init_netconsole(void)
                                goto fail;
                        }
                        /* Dump existing printks when we register */
-                       if (nt->extended)
-                               netconsole_ext.flags |= CON_PRINTBUFFER |
-                                                       CON_ENABLED;
-                       else
+                       if (nt->extended) {
+                               extended = true;
+                               netconsole_ext.flags |= CON_PRINTBUFFER;
+                       } else {
                                netconsole.flags |= CON_PRINTBUFFER;
+                       }
 
                        spin_lock_irqsave(&target_list_lock, flags);
                        list_add(&nt->list, &target_list);
@@ -915,7 +915,7 @@ static int __init init_netconsole(void)
        if (err)
                goto undonotifier;
 
-       if (netconsole_ext.flags & CON_ENABLED)
+       if (extended)
                register_console(&netconsole_ext);
        register_console(&netconsole);
        pr_info("network logging started\n");
@@ -945,7 +945,8 @@ static void __exit cleanup_netconsole(void)
 {
        struct netconsole_target *nt, *tmp;
 
-       unregister_console(&netconsole_ext);
+       if (console_is_registered(&netconsole_ext))
+               unregister_console(&netconsole_ext);
        unregister_console(&netconsole);
        dynamic_netconsole_exit();
        unregister_netdevice_notifier(&netconsole_netdev_notifier);