[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: Ralph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 13 insertions, 13 deletions

diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 181b51772b1b..a817dade37c0 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -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) {
-                        put_device(dev);
-                        device_unregister(dev);
-                        continue;
+                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;
 }