more patches for this tty open race

1 files changed, 76 insertions, 0 deletions

diff --git a/tty-open-hangup-race-fixup.patch b/tty-open-hangup-race-fixup.patch
new file mode 100644
index 000000000..cda7f41b3
--- /dev/null
+++ b/tty-open-hangup-race-fixup.patch
@@ -0,0 +1,76 @@
+From 9e88e8b9915b5e067507a087437d80e6a133d612 Mon Sep 17 00:00:00 2001
+From: Jiri Slaby <jslaby@suse.cz>
+Date: Sat, 27 Nov 2010 16:06:46 +0100
+Subject: [PATCH 1/1] TTY: open/hangup race fixup
+
+
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+---
+ drivers/tty/tty_io.c |   10 +++++++++-
+ include/linux/tty.h  |    1 +
+ 2 files changed, 10 insertions(+), 1 deletions(-)
+
+diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
+index 878f6d6..35480dd 100644
+--- a/drivers/tty/tty_io.c
++++ b/drivers/tty/tty_io.c
+@@ -559,6 +559,9 @@ void __tty_hangup(struct tty_struct *tty)
+ 
+ 	tty_lock();
+ 
++	/* some functions below drop BTM, so we need this bit */
++	set_bit(TTY_HUPPING, &tty->flags);
++
+ 	/* inuse_filps is protected by the single tty lock,
+ 	   this really needs to change if we want to flush the
+ 	   workqueue with the lock held */
+@@ -578,6 +581,10 @@ void __tty_hangup(struct tty_struct *tty)
+ 	}
+ 	spin_unlock(&tty_files_lock);
+ 
++	/*
++	 * it drops BTM and thus races with reopen
++	 * we protect the race by TTY_HUPPING
++	 */
+ 	tty_ldisc_hangup(tty);
+ 
+ 	read_lock(&tasklist_lock);
+@@ -615,7 +622,6 @@ void __tty_hangup(struct tty_struct *tty)
+ 	tty->session = NULL;
+ 	tty->pgrp = NULL;
+ 	tty->ctrl_status = 0;
+-	set_bit(TTY_HUPPED, &tty->flags);
+ 	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
+ 
+ 	/* Account for the p->signal references we killed */
+@@ -641,6 +647,7 @@ void __tty_hangup(struct tty_struct *tty)
+ 	 * can't yet guarantee all that.
+ 	 */
+ 	set_bit(TTY_HUPPED, &tty->flags);
++	clear_bit(TTY_HUPPING, &tty->flags);
+ 	tty_ldisc_enable(tty);
+ 
+ 	tty_unlock();
+@@ -1311,6 +1318,7 @@ static int tty_reopen(struct tty_struct *tty)
+ 	struct tty_driver *driver = tty->driver;
+ 
+ 	if (test_bit(TTY_CLOSING, &tty->flags) ||
++			test_bit(TTY_HUPPING, &tty->flags) ||
+ 			test_bit(TTY_LDISC_CHANGING, &tty->flags))
+ 		return -EIO;
+ 
+diff --git a/include/linux/tty.h b/include/linux/tty.h
+index 032d79f..54e4eaa 100644
+--- a/include/linux/tty.h
++++ b/include/linux/tty.h
+@@ -366,6 +366,7 @@ struct tty_file_private {
+ #define TTY_HUPPED 		18	/* Post driver->hangup() */
+ #define TTY_FLUSHING		19	/* Flushing to ldisc in progress */
+ #define TTY_FLUSHPENDING	20	/* Queued buffer flush pending */
++#define TTY_HUPPING 		21	/* ->hangup() in progress */
+ 
+ #define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
+ 
+-- 
+1.7.3.1
+