diff mbox series

[printk,v2,36/38] proc: consoles: use console_list_lock for list iteration

Message ID 20221019145600.1282823-37-john.ogness@linutronix.de
State New
Headers
Series reduce console_lock scope |

Commit Message

John Ogness Oct. 19, 2022, 2:55 p.m. UTC 
  The console_lock is used in part to guarantee safe list iteration.
The console_list_lock should be used because list synchronization
repsponsibility will be removed from the console_lock in a later
change.

Note, the console_lock is still needed to stop console printing.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 fs/proc/consoles.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

Comments

Petr Mladek Oct. 27, 2022, 12:02 p.m. UTC | #1 
On Wed 2022-10-19 17:01:58, John Ogness wrote:
> The console_lock is used in part to guarantee safe list iteration.
> The console_list_lock should be used because list synchronization
> repsponsibility will be removed from the console_lock in a later
> change.
> 
> Note, the console_lock is still needed to stop console printing.
> 
> Signed-off-by: John Ogness <john.ogness@linutronix.de>

Reviewed-by: Petr Mladek <pmladek@suse.com>

Best Regards,
Petr
diff mbox series

Patch

diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index 32512b477605..77409b176569 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -33,7 +33,15 @@  static int show_console_dev(struct seq_file *m, void *v)
 	if (con->device) {
 		const struct tty_driver *driver;
 		int index;
+
+		/*
+		 * Stop console printing because the device() callback may
+		 * assume the console is not within its write() callback.
+		 */
+		console_lock();
 		driver = con->device(con, &index);
+		console_unlock();
+
 		if (driver) {
 			dev = MKDEV(driver->major, driver->minor_start);
 			dev += index;
@@ -64,14 +72,11 @@  static void *c_start(struct seq_file *m, loff_t *pos)
 	loff_t off = 0;
 
 	/*
-	 * Stop console printing because the device() callback may
-	 * assume the console is not within its write() callback.
-	 *
-	 * Hold the console_lock to guarantee safe traversal of the
+	 * Hold the console_list_lock to guarantee safe traversal of the
 	 * console list. SRCU cannot be used because there is no
 	 * place to store the SRCU cookie.
 	 */
-	console_lock();
+	console_list_lock();
 	for_each_console(con)
 		if (off++ == *pos)
 			break;
@@ -89,7 +94,7 @@  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 = {