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authorPeter Hurley <peter@hurleysoftware.com>2013-11-07 14:01:57 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-11-25 09:17:49 -0800
commitaebf045382edb32bd763d8edea02a559e7dc41e9 (patch)
treeeeba9a7cacf8a5a14500af01eaf626839655a480 /drivers/tty
parentd4855e1fc03c2bb32dd64badf51cec5a2a26ab2a (diff)
downloadop-kernel-dev-aebf045382edb32bd763d8edea02a559e7dc41e9.zip
op-kernel-dev-aebf045382edb32bd763d8edea02a559e7dc41e9.tar.gz
n_tty: Protect minimum_to_wake reset for concurrent readers
With multiple, concurrent readers (each waiting to acquire the atomic_read_lock mutex), a departing reader may mistakenly reset minimum_to_wake after a new reader has already set a new value. Protect the minimum_to_wake reset with the atomic_read_lock critical section. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/n_tty.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index c222a56..0f74945 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2249,12 +2249,12 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
n_tty_set_room(tty);
up_read(&tty->termios_rwsem);
- mutex_unlock(&ldata->atomic_read_lock);
remove_wait_queue(&tty->read_wait, &wait);
-
if (!waitqueue_active(&tty->read_wait))
ldata->minimum_to_wake = minimum;
+ mutex_unlock(&ldata->atomic_read_lock);
+
__set_current_state(TASK_RUNNING);
if (b - buf)
retval = b - buf;
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