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>

5 files changed, 22 insertions, 18 deletions

diff --git a/arch/um/drivers/chan.h b/arch/um/drivers/chan.h
index 78f1b8999964..c512b0306dd4 100644
--- a/arch/um/drivers/chan.h
+++ b/arch/um/drivers/chan.h
@@ -37,7 +37,7 @@ extern int console_write_chan(struct chan *chan, const char *buf,
 extern int console_open_chan(struct line *line, struct console *co);
 extern void deactivate_chan(struct chan *chan, int irq);
 extern void reactivate_chan(struct chan *chan, int irq);
-extern void chan_enable_winch(struct chan *chan, struct tty_struct *tty);
+extern void chan_enable_winch(struct chan *chan, struct tty_port *port);
 extern int enable_chan(struct line *line);
 extern void close_chan(struct line *line);
 extern int chan_window_size(struct line *line, 
diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 15c553c239a1..80b47cb71e0a 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -122,10 +122,10 @@ static int open_chan(struct list_head *chans)
         return err;
 }
 
-void chan_enable_winch(struct chan *chan, struct tty_struct *tty)
+void chan_enable_winch(struct chan *chan, struct tty_port *port)
 {
         if (chan && chan->primary && chan->ops->winch)
-                register_winch(chan->fd, tty);
+                register_winch(chan->fd, port);
 }
 
 static void line_timer_cb(struct work_struct *work)
diff --git a/arch/um/drivers/chan_user.c b/arch/um/drivers/chan_user.c
index 9be670ad23b5..3fd7c3efdb18 100644
--- a/arch/um/drivers/chan_user.c
+++ b/arch/um/drivers/chan_user.c
@@ -216,7 +216,7 @@ static int winch_thread(void *arg)
         }
 }
 
-static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out,
+static int winch_tramp(int fd, struct tty_port *port, int *fd_out,
                        unsigned long *stack_out)
 {
         struct winch_data data;
@@ -271,7 +271,7 @@ static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out,
         return err;
 }
 
-void register_winch(int fd, struct tty_struct *tty)
+void register_winch(int fd, struct tty_port *port)
 {
         unsigned long stack;
         int pid, thread, count, thread_fd = -1;
@@ -281,17 +281,17 @@ void register_winch(int fd, struct tty_struct *tty)
                 return;
 
         pid = tcgetpgrp(fd);
-        if (is_skas_winch(pid, fd, tty)) {
-                register_winch_irq(-1, fd, -1, tty, 0);
+        if (is_skas_winch(pid, fd, port)) {
+                register_winch_irq(-1, fd, -1, port, 0);
                 return;
         }
 
         if (pid == -1) {
-                thread = winch_tramp(fd, tty, &thread_fd, &stack);
+                thread = winch_tramp(fd, port, &thread_fd, &stack);
                 if (thread < 0)
                         return;
 
-                register_winch_irq(thread_fd, fd, thread, tty, stack);
+                register_winch_irq(thread_fd, fd, thread, port, stack);
 
                 count = write(thread_fd, &c, sizeof(c));
                 if (count != sizeof(c))
diff --git a/arch/um/drivers/chan_user.h b/arch/um/drivers/chan_user.h
index dc693298eb8f..03f1b565c5f9 100644
--- a/arch/um/drivers/chan_user.h
+++ b/arch/um/drivers/chan_user.h
@@ -38,10 +38,10 @@ extern int generic_window_size(int fd, void *unused, unsigned short *rows_out,
                                unsigned short *cols_out);
 extern void generic_free(void *data);
 
-struct tty_struct;
-extern void register_winch(int fd,  struct tty_struct *tty);
+struct tty_port;
+extern void register_winch(int fd,  struct tty_port *port);
 extern void register_winch_irq(int fd, int tty_fd, int pid,
-                               struct tty_struct *tty, unsigned long stack);
+                               struct tty_port *port, unsigned long stack);
 
 #define __channel_help(fn, prefix) \
 __uml_help(fn, prefix "[0-9]*=<channel description>\n" \
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);
 }