Without this the application that use the mkiss line discipline have
no way to terminate in case the corresponding serial device is
removed, for example when a USB TNC is unplugged. The application must
wait on poll().
The kissattach application must be patched to take advantage of this
feature.
Signed-off-by: Jean-Christian de Rivaz <j...@eclis.ch>
---
drivers/net/hamradio/mkiss.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
index fba41e9..50cd36c 100644
--- a/drivers/net/hamradio/mkiss.c
+++ b/drivers/net/hamradio/mkiss.c
@@ -893,6 +893,20 @@ static long mkiss_compat_ioctl(struct tty_struct *tty,
struct file *file,
#endif
/*
+ * Waiting until hangup is the only allowed operation. This is used
+ * to notify the application in case the serial deivce is removed
+ * (ex. USB). The tty_ldisc_hangup() will wake up the process.
+ */
+static unsigned int mkiss_poll(struct tty_struct *tty, struct file *file,
+ poll_table *wait)
+{
+ poll_wait(file, &tty->read_wait, wait);
+ poll_wait(file, &tty->write_wait, wait);
+
+ return 0;
+}
+
+/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of data has been received, which can now be decapsulated
@@ -969,6 +983,7 @@ static struct tty_ldisc_ops ax_ldisc = {
#ifdef CONFIG_COMPAT
.compat_ioctl = mkiss_compat_ioctl,
#endif
+ .poll = mkiss_poll,
.receive_buf = mkiss_receive_buf,
.write_wakeup = mkiss_write_wakeup
};
--
1.7.10.4
--
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