[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>
diff --git a/drivers/s390/char/con3270.c b/drivers/s390/char/con3270.c
index d028d2e..ed5396d 100644
--- a/drivers/s390/char/con3270.c
+++ b/drivers/s390/char/con3270.c
@@ -64,7 +64,7 @@
#define CON_UPDATE_ERASE 1 /* Use EWRITEA instead of WRITE. */
#define CON_UPDATE_LIST 2 /* Update lines in tty3270->update. */
#define CON_UPDATE_STATUS 4 /* Update status line. */
-#define CON_UPDATE_ALL 7
+#define CON_UPDATE_ALL 8 /* Recreate screen. */
static void con3270_update(struct con3270 *);
@@ -73,18 +73,10 @@
*/
static void con3270_set_timer(struct con3270 *cp, int expires)
{
- if (expires == 0) {
- if (timer_pending(&cp->timer))
- del_timer(&cp->timer);
- return;
- }
- if (timer_pending(&cp->timer) &&
- mod_timer(&cp->timer, jiffies + expires))
- return;
- cp->timer.function = (void (*)(unsigned long)) con3270_update;
- cp->timer.data = (unsigned long) cp;
- cp->timer.expires = jiffies + expires;
- add_timer(&cp->timer);
+ if (expires == 0)
+ del_timer(&cp->timer);
+ else
+ mod_timer(&cp->timer, jiffies + expires);
}
/*
@@ -225,6 +217,12 @@
spin_lock_irqsave(&cp->view.lock, flags);
updated = 0;
+ if (cp->update_flags & CON_UPDATE_ALL) {
+ con3270_rebuild_update(cp);
+ con3270_update_status(cp);
+ cp->update_flags = CON_UPDATE_ERASE | CON_UPDATE_LIST |
+ CON_UPDATE_STATUS;
+ }
if (cp->update_flags & CON_UPDATE_ERASE) {
/* Use erase write alternate to initialize display. */
raw3270_request_set_cmd(wrq, TC_EWRITEA);
@@ -302,7 +300,6 @@
deactivate = 1;
break;
case 0x6d: /* clear: start from scratch. */
- con3270_rebuild_update(cp);
cp->update_flags = CON_UPDATE_ALL;
con3270_set_timer(cp, 1);
break;
@@ -382,30 +379,21 @@
static int
con3270_activate(struct raw3270_view *view)
{
- unsigned long flags;
struct con3270 *cp;
cp = (struct con3270 *) view;
- spin_lock_irqsave(&cp->view.lock, flags);
- cp->nr_up = 0;
- con3270_rebuild_update(cp);
- con3270_update_status(cp);
cp->update_flags = CON_UPDATE_ALL;
con3270_set_timer(cp, 1);
- spin_unlock_irqrestore(&cp->view.lock, flags);
return 0;
}
static void
con3270_deactivate(struct raw3270_view *view)
{
- unsigned long flags;
struct con3270 *cp;
cp = (struct con3270 *) view;
- spin_lock_irqsave(&cp->view.lock, flags);
del_timer(&cp->timer);
- spin_unlock_irqrestore(&cp->view.lock, flags);
}
static int
@@ -504,6 +492,7 @@
con3270_cline_end(cp);
}
/* Setup timer to output current console buffer after 1/10 second */
+ cp->nr_up = 0;
if (cp->view.dev && !timer_pending(&cp->timer))
con3270_set_timer(cp, HZ/10);
spin_unlock_irqrestore(&cp->view.lock,flags);
@@ -624,7 +613,8 @@
INIT_LIST_HEAD(&condev->lines);
INIT_LIST_HEAD(&condev->update);
- init_timer(&condev->timer);
+ setup_timer(&condev->timer, (void (*)(unsigned long)) con3270_update,
+ (unsigned long) condev);
tasklet_init(&condev->readlet,
(void (*)(unsigned long)) con3270_read_tasklet,
(unsigned long) condev->read);