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Commit c6a48264 authored by Ralph Wuerthner's avatar Ralph Wuerthner Committed by Heiko Carstens
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[S390] zcrypt: Fix possible dead lock in AP bus module. 



If a AP device is unconfigured __ap_poll_all() will call
device_unregister() in software interrupt context which can cause
dead locks. To fix this the device will be only marked as unconfigured
and the device_unregister() call will be done later by either
ap_scan_bus() or ap_queue_message() in process context.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarRalph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
parent 25c61a1f

drivers/s390/crypto/ap_bus.c

+13 −13
Original line number Diff line number Diff line
@@ -757,10 +757,16 @@ static void ap_scan_bus(struct work_struct *unused) 
				      (void *)(unsigned long)qid,

				      __ap_scan_bus);

		rc = ap_query_queue(qid, &queue_depth, &device_type);

		if (dev && rc) {

		if (dev) {

			ap_dev = to_ap_dev(dev);

			spin_lock_bh(&ap_dev->lock);

			if (rc || ap_dev->unregistered) {

				spin_unlock_bh(&ap_dev->lock);

				put_device(dev);

				device_unregister(dev);

				continue;

			} else

				spin_unlock_bh(&ap_dev->lock);

		}

		if (dev) {

			put_device(dev);
@@ -994,7 +1000,7 @@ void ap_queue_message(struct ap_device *ap_dev, struct ap_message *ap_msg) 
			ap_dev->unregistered = 1;

	} else {

		ap_dev->drv->receive(ap_dev, ap_msg, ERR_PTR(-ENODEV));

		rc = 0;

		rc = -ENODEV;

	}

	spin_unlock_bh(&ap_dev->lock);

	if (rc == -ENODEV)
@@ -1044,18 +1050,12 @@ static void ap_poll_timeout(unsigned long unused) 
 */

static int __ap_poll_all(struct ap_device *ap_dev, unsigned long *flags)

{

	int rc;



	spin_lock(&ap_dev->lock);

	if (!ap_dev->unregistered) {

		rc = ap_poll_queue(ap_dev, flags);

		if (rc)

		if (ap_poll_queue(ap_dev, flags))

			ap_dev->unregistered = 1;

	} else

		rc = 0;

	}

	spin_unlock(&ap_dev->lock);

	if (rc)

		device_unregister(&ap_dev->device);

	return 0;

}