linux-kernel - [PATCH printk 07/18] printk: Convert console list walks for readers to list lock

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Date:   Sat, 24 Sep 2022 02:10:43 +0206
From:   John Ogness <john.ogness@...utronix.de>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-fsdevel@...r.kernel.org
Subject: [PATCH printk 07/18] printk: Convert console list walks for readers to list lock

From: Thomas Gleixner <tglx@...utronix.de>

Facilities which expose console information to sysfs or procfs can use the
new list protection to keep the list stable. No need to hold console lock.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: John Ogness <john.ogness@...utronix.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 drivers/tty/tty_io.c   | 6 +++---
 fs/proc/consoles.c     | 6 +++---
 kernel/printk/printk.c | 8 ++++----
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8fec1d8648f5..6fa142155b94 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -3535,8 +3535,8 @@ static ssize_t show_cons_active(struct device *dev,
 	struct console *c;
 	ssize_t count = 0;
 
-	console_lock();
-	for_each_console(c) {
+	console_list_lock();
+	for_each_registered_console(c) {
 		if (!c->device)
 			continue;
 		if (!c->write)
@@ -3560,7 +3560,7 @@ static ssize_t show_cons_active(struct device *dev,
 
 		count += sprintf(buf + count, "%c", i ? ' ':'\n');
 	}
-	console_unlock();
+	console_list_unlock();
 
 	return count;
 }
diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index dfe6ce3505ce..6775056eecd5 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -63,8 +63,8 @@ static void *c_start(struct seq_file *m, loff_t *pos)
 	struct console *con;
 	loff_t off = 0;
 
-	console_lock();
-	for_each_console(con)
+	console_list_lock();
+	for_each_registered_console(con)
 		if (off++ == *pos)
 			break;
 
@@ -80,7 +80,7 @@ static void *c_next(struct seq_file *m, void *v, loff_t *pos)
 
 static void c_stop(struct seq_file *m, void *v)
 {
-	console_unlock();
+	console_list_unlock();
 }
 
 static const struct seq_operations consoles_op = {
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 8c56f6071873..80a728ef9d96 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2990,18 +2990,18 @@ void console_flush_on_panic(enum con_flush_mode mode)
  */
 struct tty_driver *console_device(int *index)
 {
-	struct console *c;
 	struct tty_driver *driver = NULL;
+	struct console *c;
 
-	console_lock();
-	for_each_console(c) {
+	console_list_lock();
+	for_each_registered_console(c) {
 		if (!c->device)
 			continue;
 		driver = c->device(c, index);
 		if (driver)
 			break;
 	}
-	console_unlock();
+	console_list_unlock();
 	return driver;
 }
 
-- 
2.30.2