From: Jiri Slaby <jslaby@suse.cz>
Date: Thu, 7 Jul 2022 10:25:57 +0200
Subject: tty: extract tty_flip_buffer_commit() from tty_flip_buffer_push()
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Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git#tty-linus
Git-commit: 716b10580283fda66f2b88140e3964f8a7f9da89
Patch-mainline: Queued in subsystem maintainer repository
References: bsc#1198829 CVE-2022-1462

We will need this new helper in the next patch.

Cc: Hillf Danton <hdanton@sina.com>
Cc: 一只狗 <chennbnbnb@gmail.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220707082558.9250-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/tty_buffer.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/tty/tty_buffer.c
+++ b/drivers/tty/tty_buffer.c
@@ -387,6 +387,15 @@ int __tty_insert_flip_char(struct tty_po
 }
 EXPORT_SYMBOL(__tty_insert_flip_char);
 
+static inline void tty_flip_buffer_commit(struct tty_buffer *tail)
+{
+	/*
+	 * Paired w/ acquire in flush_to_ldisc(); ensures flush_to_ldisc() sees
+	 * buffer data.
+	 */
+	smp_store_release(&tail->commit, tail->used);
+}
+
 /**
  *	tty_schedule_flip	-	push characters to ldisc
  *	@port: tty port to push from
@@ -400,10 +409,7 @@ void tty_schedule_flip(struct tty_port *
 {
 	struct tty_bufhead *buf = &port->buf;
 
-	/* paired w/ acquire in flush_to_ldisc(); ensures
-	 * flush_to_ldisc() sees buffer data.
-	 */
-	smp_store_release(&buf->tail->commit, buf->tail->used);
+	tty_flip_buffer_commit(buf->tail);
 	queue_work(system_unbound_wq, &buf->work);
 }
 EXPORT_SYMBOL(tty_schedule_flip);