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Commit 205d7ab9 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

[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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent fcf7581f

drivers/s390/char/con3270.c

+14 −24
Original line number Diff line number Diff line
@@ -64,7 +64,7 @@ static struct con3270 *condev; 
#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_update(struct con3270 *); 
 */

static void con3270_set_timer(struct con3270 *cp, int expires)

{

	if (expires == 0) {

		if (timer_pending(&cp->timer))

	if (expires == 0)

		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);

	else

		mod_timer(&cp->timer, jiffies + expires);

}



/*
@@ -225,6 +217,12 @@ con3270_update(struct con3270 *cp) 


	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 @@ con3270_read_tasklet(struct raw3270_request *rrq) 
		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 @@ con3270_issue_read(struct con3270 *cp) 
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_write(struct console *co, const char *str, unsigned int count) 
			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 @@ con3270_init(void) 


	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);

drivers/s390/char/tty3270.c

+18 −24
Original line number Diff line number Diff line
@@ -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);