um: Use tty_port in SIGWINCH handler

The tty below tty_port might get destroyed by the tty layer
while we hold a reference to it.
So we have to carry tty_port around...

Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 10 insertions, 6 deletions

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 232243aec70c..be541cf69fd2 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -305,7 +305,7 @@ static int line_activate(struct tty_port *port, struct tty_struct *tty)
 		return ret;
 
 	if (!line->sigio) {
-		chan_enable_winch(line->chan_out, tty);
+		chan_enable_winch(line->chan_out, port);
 		line->sigio = 1;
 	}
 
@@ -603,7 +603,7 @@ struct winch {
 	int fd;
 	int tty_fd;
 	int pid;
-	struct tty_struct *tty;
+	struct tty_port *port;
 	unsigned long stack;
 	struct work_struct work;
 };
@@ -657,7 +657,7 @@ static irqreturn_t winch_interrupt(int irq, void *data)
 			goto out;
 		}
 	}
-	tty = winch->tty;
+	tty = tty_port_tty_get(winch->port);
 	if (tty != NULL) {
 		line = tty->driver_data;
 		if (line != NULL) {
@@ -665,6 +665,7 @@ static irqreturn_t winch_interrupt(int irq, void *data)
 					 &tty->winsize.ws_col);
 			kill_pgrp(tty->pgrp, SIGWINCH, 1);
 		}
+		tty_kref_put(tty);
 	}
  out:
 	if (winch->fd != -1)
@@ -672,7 +673,7 @@ static irqreturn_t winch_interrupt(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
-void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
+void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
 			unsigned long stack)
 {
 	struct winch *winch;
@@ -687,7 +688,7 @@ void register_winch_irq(int fd, int tty_fd, int pid, struct tty_struct *tty,
 				   .fd  	= fd,
 				   .tty_fd 	= tty_fd,
 				   .pid  	= pid,
-				   .tty 	= tty,
+				   .port 	= port,
 				   .stack	= stack });
 
 	if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
@@ -716,15 +717,18 @@ static void unregister_winch(struct tty_struct *tty)
 {
 	struct list_head *ele, *next;
 	struct winch *winch;
+	struct tty_struct *wtty;
 
 	spin_lock(&winch_handler_lock);
 
 	list_for_each_safe(ele, next, &winch_handlers) {
 		winch = list_entry(ele, struct winch, list);
-		if (winch->tty == tty) {
+		wtty = tty_port_tty_get(winch->port);
+		if (wtty == tty) {
 			free_winch(winch);
 			break;
 		}
+		tty_kref_put(wtty);
 	}
 	spin_unlock(&winch_handler_lock);
 }