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 <pe...@hurleysoftware.com>
---
drivers/tty/n_tty.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index ce11cd5..bf9650d 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -2253,12 +2253,12 @@ 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;
--
1.8.1.2
--
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