[S390] zcrypt device registration/unregistration race.

Fix a race condition during AP device registration and unregistration.

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

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 6ed0985c0c91ca2c61730d9121cc52dd080119a2..cd30f37fceae4512b3c99088a006ced4c6eb5600 100644 (file)
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -449,8 +449,6 @@ static int ap_device_probe(struct device *dev)
 
        ap_dev->drv = ap_drv;
        rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV;
-       if (rc)
-               ap_dev->unregistered = 1;
        return rc;
 }
 
@@ -487,14 +485,7 @@ static int ap_device_remove(struct device *dev)
        struct ap_device *ap_dev = to_ap_dev(dev);
        struct ap_driver *ap_drv = ap_dev->drv;
 
-       spin_lock_bh(&ap_dev->lock);
-       __ap_flush_queue(ap_dev);
-       /**
-        * set ->unregistered to 1 while holding the lock. This prevents
-        * new messages to be put on the queue from now on.
-        */
-       ap_dev->unregistered = 1;
-       spin_unlock_bh(&ap_dev->lock);
+       ap_flush_queue(ap_dev);
        if (ap_drv->remove)
                ap_drv->remove(ap_dev);
        return 0;
@@ -763,6 +754,7 @@ static void ap_scan_bus(void *data)
                        break;
                ap_dev->qid = qid;
                ap_dev->queue_depth = queue_depth;
+               ap_dev->unregistered = 1;
                spin_lock_init(&ap_dev->lock);
                INIT_LIST_HEAD(&ap_dev->pendingq);
                INIT_LIST_HEAD(&ap_dev->requestq);
@@ -784,7 +776,12 @@ static void ap_scan_bus(void *data)
                /* Add device attributes. */
                rc = sysfs_create_group(&ap_dev->device.kobj,
                                        &ap_dev_attr_group);
-               if (rc)
+               if (!rc) {
+                       spin_lock_bh(&ap_dev->lock);
+                       ap_dev->unregistered = 0;
+                       spin_unlock_bh(&ap_dev->lock);
+               }
+               else
                        device_unregister(&ap_dev->device);
        }
 }
@@ -970,6 +967,8 @@ void ap_queue_message(struct ap_device *ap_dev, struct ap_message *ap_msg)
                        rc = __ap_queue_message(ap_dev, ap_msg);
                if (!rc)
                        wake_up(&ap_poll_wait);
+               if (rc == -ENODEV)
+                       ap_dev->unregistered = 1;
        } else {
                ap_dev->drv->receive(ap_dev, ap_msg, ERR_PTR(-ENODEV));
                rc = 0;
@@ -1028,6 +1027,8 @@ static int __ap_poll_all(struct device *dev, void *data)
        spin_lock(&ap_dev->lock);
        if (!ap_dev->unregistered) {
                rc = ap_poll_queue(to_ap_dev(dev), (unsigned long *) data);
+               if (rc)
+                       ap_dev->unregistered = 1;
        } else
                rc = 0;
        spin_unlock(&ap_dev->lock);