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>
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@ -2249,12 +2249,12 @@ static ssize_t n_tty_read(struct tty_struct *tty, struct file *file,
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n_tty_set_room(tty);
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up_read(&tty->termios_rwsem);
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mutex_unlock(&ldata->atomic_read_lock);
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remove_wait_queue(&tty->read_wait, &wait);
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if (!waitqueue_active(&tty->read_wait))
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ldata->minimum_to_wake = minimum;
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mutex_unlock(&ldata->atomic_read_lock);
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__set_current_state(TASK_RUNNING);
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if (b - buf)
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retval = b - buf;
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