[S390] 3270: lock dependency fixes

Lockdep found a problem with the lock order of the view lock and the
ccw device lock. raw3270_activate_view/raw3270_deactivate_view first
take the ccw device lock then call the activate/deactivate functions
of the view which take view lock. The update functions of the
con3270/tty3270 view will first take the view lock, then take the
ccw device lock. To fix this the activate/deactivate functions are
changed to avoid taking the view lock by moving the functions calls
that modify the 3270 output buffer to the update function which is
called by a timer.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 18 insertions, 24 deletions

diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
index aa7a114f6529..38385677c653 100644
--- a/drivers/s390/char/tty3270.c
+++ b/drivers/s390/char/tty3270.c
@@ -112,7 +112,7 @@ struct tty3270 {
 #define TTY_UPDATE_LIST         2       /* Update lines in tty3270->update. */
 #define TTY_UPDATE_INPUT        4       /* Update input line. */
 #define TTY_UPDATE_STATUS       8       /* Update status line. */
-#define TTY_UPDATE_ALL          15
+#define TTY_UPDATE_ALL          16      /* Recreate screen. */
 
 static void tty3270_update(struct tty3270 *);
 
@@ -121,19 +121,10 @@ static void tty3270_update(struct tty3270 *);
  */
 static void tty3270_set_timer(struct tty3270 *tp, int expires)
 {
-        if (expires == 0) {
-                if (timer_pending(&tp->timer) && del_timer(&tp->timer))
-                        raw3270_put_view(&tp->view);
-                return;
-        }
-        if (timer_pending(&tp->timer) &&
-            mod_timer(&tp->timer, jiffies + expires))
-                return;
-        raw3270_get_view(&tp->view);
-        tp->timer.function = (void (*)(unsigned long)) tty3270_update;
-        tp->timer.data = (unsigned long) tp;
-        tp->timer.expires = jiffies + expires;
-        add_timer(&tp->timer);
+        if (expires == 0)
+                del_timer(&tp->timer);
+        else
+                mod_timer(&tp->timer, jiffies + expires);
 }
 
 /*
@@ -337,7 +328,6 @@ tty3270_write_callback(struct raw3270_request *rq, void *data)
         tp = (struct tty3270 *) rq->view;
         if (rq->rc != 0) {
                 /* Write wasn't successfull. Refresh all. */
-                tty3270_rebuild_update(tp);
                 tp->update_flags = TTY_UPDATE_ALL;
                 tty3270_set_timer(tp, 1);
         }
@@ -366,6 +356,12 @@ tty3270_update(struct tty3270 *tp)
 
         spin_lock(&tp->view.lock);
         updated = 0;
+        if (tp->update_flags & TTY_UPDATE_ALL) {
+                tty3270_rebuild_update(tp);
+                tty3270_update_status(tp);
+                tp->update_flags = TTY_UPDATE_ERASE | TTY_UPDATE_LIST |
+                        TTY_UPDATE_INPUT | TTY_UPDATE_STATUS;
+        }
         if (tp->update_flags & TTY_UPDATE_ERASE) {
                 /* Use erase write alternate to erase display. */
                 raw3270_request_set_cmd(wrq, TC_EWRITEA);
@@ -425,7 +421,6 @@ tty3270_update(struct tty3270 *tp)
                 xchg(&tp->write, wrq);
         }
         spin_unlock(&tp->view.lock);
-        raw3270_put_view(&tp->view);
 }
 
 /*
@@ -570,7 +565,6 @@ tty3270_read_tasklet(struct raw3270_request *rrq)
                 tty3270_set_timer(tp, 1);
         } else if (tp->input->string[0] == 0x6d) {
                 /* Display has been cleared. Redraw. */
-                tty3270_rebuild_update(tp);
                 tp->update_flags = TTY_UPDATE_ALL;
                 tty3270_set_timer(tp, 1);
         }
@@ -641,22 +635,20 @@ static int
 tty3270_activate(struct raw3270_view *view)
 {
         struct tty3270 *tp;
-        unsigned long flags;
 
         tp = (struct tty3270 *) view;
-        spin_lock_irqsave(&tp->view.lock, flags);
-        tp->nr_up = 0;
-        tty3270_rebuild_update(tp);
-        tty3270_update_status(tp);
         tp->update_flags = TTY_UPDATE_ALL;
         tty3270_set_timer(tp, 1);
-        spin_unlock_irqrestore(&tp->view.lock, flags);
         return 0;
 }
 
 static void
 tty3270_deactivate(struct raw3270_view *view)
 {
+        struct tty3270 *tp;
+
+        tp = (struct tty3270 *) view;
+        del_timer(&tp->timer);
 }
 
 static int
@@ -743,6 +735,7 @@ tty3270_free_view(struct tty3270 *tp)
 {
         int pages;
 
+        del_timer_sync(&tp->timer);
         kbd_free(tp->kbd);
         raw3270_request_free(tp->kreset);
         raw3270_request_free(tp->read);
@@ -889,7 +882,8 @@ tty3270_open(struct tty_struct *tty, struct file * filp)
         INIT_LIST_HEAD(&tp->update);
         INIT_LIST_HEAD(&tp->rcl_lines);
         tp->rcl_max = 20;
-        init_timer(&tp->timer);
+        setup_timer(&tp->timer, (void (*)(unsigned long)) tty3270_update,
+                    (unsigned long) tp);
         tasklet_init(&tp->readlet, 
                      (void (*)(unsigned long)) tty3270_read_tasklet,
                      (unsigned long) tp->read);