linux-kernel - [PATCH 1/2] tty: Export redirect release

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Date:   Mon, 23 Nov 2020 18:49:01 -0600
From:   minyard@....org
To:     Jiri Slaby <jirislaby@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Peter Hurley <peter@...leysoftware.com>,
        brian.bloniarz@...il.com, Corey Minyard <cminyard@...sta.com>
Subject: [PATCH 1/2] tty: Export redirect release

From: Corey Minyard <cminyard@...sta.com>

This will be required by the pty code when it removes tty_vhangup() on
master close.

Signed-off-by: Corey Minyard <cminyard@...sta.com>
---
 drivers/tty/tty_io.c | 32 ++++++++++++++++++++++++--------
 include/linux/tty.h  |  1 +
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 7a4c02548fb3..571b1d7d4d5a 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -542,6 +542,28 @@ void tty_wakeup(struct tty_struct *tty)
 
 EXPORT_SYMBOL_GPL(tty_wakeup);
 
+/**
+ *	tty_release_redirect	-	Release a redirect on a pty if present
+ *	@tty: tty device
+ *
+ *	This is available to the pty code so if the master closes, if the
+ *	slave is a redirect it can release the redirect.
+ */
+struct file *tty_release_redirect(struct tty_struct *tty)
+{
+	struct file *f = NULL;
+
+	spin_lock(&redirect_lock);
+	if (redirect && file_tty(redirect) == tty) {
+		f = redirect;
+		redirect = NULL;
+	}
+	spin_unlock(&redirect_lock);
+
+	return f;
+}
+EXPORT_SYMBOL_GPL(tty_release_redirect);
+
 /**
  *	__tty_hangup		-	actual handler for hangup events
  *	@tty: tty device
@@ -567,7 +589,7 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
 static void __tty_hangup(struct tty_struct *tty, int exit_session)
 {
 	struct file *cons_filp = NULL;
-	struct file *filp, *f = NULL;
+	struct file *filp, *f;
 	struct tty_file_private *priv;
 	int    closecount = 0, n;
 	int refs;
@@ -575,13 +597,7 @@ static void __tty_hangup(struct tty_struct *tty, int exit_session)
 	if (!tty)
 		return;
 
-
-	spin_lock(&redirect_lock);
-	if (redirect && file_tty(redirect) == tty) {
-		f = redirect;
-		redirect = NULL;
-	}
-	spin_unlock(&redirect_lock);
+	f = tty_release_redirect(tty);
 
 	tty_lock(tty);
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index a99e9b8e4e31..d98319c5d195 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -418,6 +418,7 @@ extern void tty_kclose(struct tty_struct *tty);
 extern int tty_dev_name_to_number(const char *name, dev_t *number);
 extern int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout);
 extern void tty_ldisc_unlock(struct tty_struct *tty);
+extern struct file *tty_release_redirect(struct tty_struct *tty);
 #else
 static inline void tty_kref_put(struct tty_struct *tty)
 { }
-- 
2.25.1