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Commit 5712f330 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

s390/3270: fix lockdep false positive on view->lock 



The spinlock in the raw3270_view structure is used by con3270, tty3270
and fs3270 in different ways. For con3270 the lock can be acquired in
irq context, for tty3270 and fs3270 the highest context is bh.

Lockdep sees the view->lock as a single class and if the 3270 driver
is used for the console the following message is generated:

WARNING: inconsistent lock state
5.1.0-rc3-05157-g5c168033979d #12 Not tainted
--------------------------------
inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
swapper/0/1 [HC0[0]:SC1[1]:HE1:SE0] takes:
(____ptrval____) (&(&view->lock)->rlock){?.-.}, at: tty3270_update+0x7c/0x330

Introduce a lockdep subclass for the view lock to distinguish bh from
irq locks.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 2cc9637c

drivers/s390/char/con3270.c

+1 −1
Original line number Diff line number Diff line
@@ -629,7 +629,7 @@ con3270_init(void) 
		     (void (*)(unsigned long)) con3270_read_tasklet,

		     (unsigned long) condev->read);



	raw3270_add_view(&condev->view, &con3270_fn, 1);

	raw3270_add_view(&condev->view, &con3270_fn, 1, RAW3270_VIEW_LOCK_IRQ);



	INIT_LIST_HEAD(&condev->freemem);

	for (i = 0; i < CON3270_STRING_PAGES; i++) {

drivers/s390/char/fs3270.c

+2 −1
Original line number Diff line number Diff line
@@ -463,7 +463,8 @@ fs3270_open(struct inode *inode, struct file *filp) 


	init_waitqueue_head(&fp->wait);

	fp->fs_pid = get_pid(task_pid(current));

	rc = raw3270_add_view(&fp->view, &fs3270_fn, minor);

	rc = raw3270_add_view(&fp->view, &fs3270_fn, minor,

			      RAW3270_VIEW_LOCK_BH);

	if (rc) {

		fs3270_free_view(&fp->view);

		goto out;

drivers/s390/char/raw3270.c

+2 −1
Original line number Diff line number Diff line
@@ -920,7 +920,7 @@ raw3270_deactivate_view(struct raw3270_view *view) 
 * Add view to device with minor "minor".

 */

int

raw3270_add_view(struct raw3270_view *view, struct raw3270_fn *fn, int minor)

raw3270_add_view(struct raw3270_view *view, struct raw3270_fn *fn, int minor, int subclass)

{

	unsigned long flags;

	struct raw3270 *rp;
@@ -942,6 +942,7 @@ raw3270_add_view(struct raw3270_view *view, struct raw3270_fn *fn, int minor) 
		view->cols = rp->cols;

		view->ascebc = rp->ascebc;

		spin_lock_init(&view->lock);

		lockdep_set_subclass(&view->lock, subclass);

		list_add(&view->list, &rp->view_list);

		rc = 0;

		spin_unlock_irqrestore(get_ccwdev_lock(rp->cdev), flags);

drivers/s390/char/raw3270.h

+3 −1
Original line number Diff line number Diff line
@@ -150,6 +150,8 @@ struct raw3270_fn { 
struct raw3270_view {

	struct list_head list;

	spinlock_t lock;

#define RAW3270_VIEW_LOCK_IRQ	0

#define RAW3270_VIEW_LOCK_BH	1

	atomic_t ref_count;

	struct raw3270 *dev;

	struct raw3270_fn *fn;
@@ -158,7 +160,7 @@ struct raw3270_view { 
	unsigned char *ascebc;		/* ascii -> ebcdic table */

};



int raw3270_add_view(struct raw3270_view *, struct raw3270_fn *, int);

int raw3270_add_view(struct raw3270_view *, struct raw3270_fn *, int, int);

int raw3270_activate_view(struct raw3270_view *);

void raw3270_del_view(struct raw3270_view *);

void raw3270_deactivate_view(struct raw3270_view *);

drivers/s390/char/tty3270.c

+2 −1
Original line number Diff line number Diff line
@@ -980,7 +980,8 @@ static int tty3270_install(struct tty_driver *driver, struct tty_struct *tty) 
		return PTR_ERR(tp);



	rc = raw3270_add_view(&tp->view, &tty3270_fn,

			      tty->index + RAW3270_FIRSTMINOR);

			      tty->index + RAW3270_FIRSTMINOR,

			      RAW3270_VIEW_LOCK_BH);

	if (rc) {

		tty3270_free_view(tp);

		return rc;