printk: fix exclusive_console replaying

Commit f92b070f2dc8 ("printk: Do not miss new messages when replaying
the log") introduced a new variable @exclusive_console_stop_seq to
store when an exclusive console should stop printing. It should be
set to the @console_seq value at registration. However, @console_seq
is previously set to @syslog_seq so that the exclusive console knows
where to begin. This results in the exclusive console immediately
reactivating all the other consoles and thus repeating the messages
for those consoles.

Set @console_seq after @exclusive_console_stop_seq has stored the
current @console_seq value.

Fixes: f92b070f2dc8 ("printk: Do not miss new messages when replaying the log")
Link: http://lkml.kernel.org/r/20191219115322.31160-1-john.ogness@linutronix.de
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 1ef6f75d92f1f6c186fd1187786023a996a7fea0..fada22dc4ab6c134e532ca7dcfc194954f40126b 100644 (file)
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2770,8 +2770,6 @@ void register_console(struct console *newcon)
                 * for us.
                 */
                logbuf_lock_irqsave(flags);
-               console_seq = syslog_seq;
-               console_idx = syslog_idx;
                /*
                 * We're about to replay the log buffer.  Only do this to the
                 * just-registered console to avoid excessive message spam to
@@ -2783,6 +2781,8 @@ void register_console(struct console *newcon)
                 */
                exclusive_console = newcon;
                exclusive_console_stop_seq = console_seq;
+               console_seq = syslog_seq;
+               console_idx = syslog_idx;
                logbuf_unlock_irqrestore(flags);
        }
        console_unlock();