linux-kernel - [PATCH] tty: Fix merge of "tty: Refactor tty

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Date:	Thu, 31 Mar 2016 17:47:07 -0700
From:	Peter Hurley <peter@...leysoftware.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-next@...r.kernel.org,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH] tty: Fix merge of "tty: Refactor tty_open()"

Commit e9036d066236 ("tty: Drop krefs for interrupted tty lock")
fixed a tty reference counting problem introduced in
commit 0bfd464d3fdd ("tty: Wait interruptibly for tty lock on reopen"),
so v4.5.0 is correct.

However, commit d6203d0c7b73 ("tty: Refactor tty_open()") moved the
relevant code for 4.6-rc1; correct the merge.

Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
 drivers/tty/tty_io.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 8d26ed7..c14c45f 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2049,14 +2049,13 @@ static struct tty_struct *tty_open_by_driver(dev_t device, struct inode *inode,
 	if (tty) {
 		mutex_unlock(&tty_mutex);
 		retval = tty_lock_interruptible(tty);
+		tty_kref_put(tty);  /* drop kref from tty_driver_lookup_tty() */
 		if (retval) {
 			if (retval == -EINTR)
 				retval = -ERESTARTSYS;
 			tty = ERR_PTR(retval);
 			goto out;
 		}
-		/* safe to drop the kref from tty_driver_lookup_tty() */
-		tty_kref_put(tty);
 		retval = tty_reopen(tty);
 		if (retval < 0) {
 			tty_unlock(tty);
-- 
2.8.0