linux-kernel - [RFC PATCH v1 16/25] printk: implement CON

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Message-Id: <20190212143003.48446-17-john.ogness@linutronix.de>
Date:   Tue, 12 Feb 2019 15:29:54 +0100
From:   John Ogness <john.ogness@...utronix.de>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Daniel Wang <wonderfly@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        Jiri Slaby <jslaby@...e.com>,
        Peter Feiner <pfeiner@...gle.com>,
        linux-serial@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: [RFC PATCH v1 16/25] printk: implement CON_PRINTBUFFER

If the CON_PRINTBUFFER flag is not set, do not replay the history
for that console.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 kernel/printk/printk.c | 25 ++++++-------------------
 1 file changed, 6 insertions(+), 19 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6c875abd7b17..b97d4195b09a 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -399,10 +399,6 @@ static u32 log_first_idx;
 static u64 log_next_seq;
 static u32 log_next_idx;
 
-/* the next printk record to write to the console */
-static u64 console_seq;
-static u32 console_idx;
-
 /* the next printk record to read after the last 'clear' command */
 static u64 clear_seq;
 static u32 clear_idx;
@@ -1596,8 +1592,12 @@ static void call_console_drivers(u64 seq, const char *ext_text, size_t ext_len,
 		if (!(con->flags & CON_ENABLED))
 			continue;
 		if (!con->wrote_history) {
-			printk_write_history(con, seq);
-			continue;
+			if (con->flags & CON_PRINTBUFFER) {
+				printk_write_history(con, seq);
+				continue;
+			}
+			con->wrote_history = 1;
+			con->printk_seq = seq - 1;
 		}
 		if (!con->write)
 			continue;
@@ -1822,8 +1822,6 @@ EXPORT_SYMBOL(printk);
 
 static u64 syslog_seq;
 static u32 syslog_idx;
-static u64 console_seq;
-static u32 console_idx;
 static u64 log_first_seq;
 static u32 log_first_idx;
 static u64 log_next_seq;
@@ -2224,7 +2222,6 @@ early_param("keep_bootcon", keep_bootcon_setup);
 void register_console(struct console *newcon)
 {
 	int i;
-	unsigned long flags;
 	struct console *bcon = NULL;
 	struct console_cmdline *c;
 	static bool has_preferred;
@@ -2340,16 +2337,6 @@ void register_console(struct console *newcon)
 	if (newcon->flags & CON_EXTENDED)
 		nr_ext_console_drivers++;
 
-	if (newcon->flags & CON_PRINTBUFFER) {
-		/*
-		 * console_unlock(); will print out the buffered messages
-		 * for us.
-		 */
-		logbuf_lock_irqsave(flags);
-		console_seq = syslog_seq;
-		console_idx = syslog_idx;
-		logbuf_unlock_irqrestore(flags);
-	}
 	console_unlock();
 	console_sysfs_notify();
 
-- 
2.11.0