isicom: redo locking to use tty port locks

This helps set the basis for moving block_til_ready into common code. We also
introduce a tty_port_hangup helper as this will also be generally needed.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 0557b6384747..9f418bca4a22 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -7,6 +7,7 @@
 #include <linux/tty.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
+#include <linux/serial.h>
 #include <linux/timer.h>
 #include <linux/string.h>
 #include <linux/slab.h>
@@ -96,6 +97,29 @@ void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
 EXPORT_SYMBOL(tty_port_tty_set);
 
 /**
+ *      tty_port_hangup         -       hangup helper
+ *      @port: tty port
+ *
+ *      Perform port level tty hangup flag and count changes. Drop the tty
+ *      reference.
+ */
+
+void tty_port_hangup(struct tty_port *port)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&port->lock, flags);
+        port->count = 0;
+        port->flags &= ~ASYNC_NORMAL_ACTIVE;
+        if (port->tty)
+                tty_kref_put(port->tty);
+        port->tty = NULL;
+        spin_unlock_irqrestore(&port->lock, flags);
+        wake_up_interruptible(&port->open_wait);
+}
+EXPORT_SYMBOL(tty_port_hangup);
+
+/**
  *      tty_port_carrier_raised -       carrier raised check
  *      @port: tty port
  *