[S390] zcrypt: fix possible race when unloading zcrypt driver modules

Move try_module_get() call into spin protected block to prevent zcrypt
driver module unload while submitting a request to driver.

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

diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
index 9976139..e3625a4 100644 (file)
--- a/drivers/s390/crypto/zcrypt_api.c
+++ b/drivers/s390/crypto/zcrypt_api.c
@@ -298,14 +298,14 @@ static long zcrypt_rsa_modexpo(struct ica_rsa_modexpo *mex)
                get_device(&zdev->ap_dev->device);
                zdev->request_count++;
                __zcrypt_decrease_preference(zdev);
-               spin_unlock_bh(&zcrypt_device_lock);
                if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+                       spin_unlock_bh(&zcrypt_device_lock);
                        rc = zdev->ops->rsa_modexpo(zdev, mex);
+                       spin_lock_bh(&zcrypt_device_lock);
                        module_put(zdev->ap_dev->drv->driver.owner);
                }
                else
                        rc = -EAGAIN;
-               spin_lock_bh(&zcrypt_device_lock);
                zdev->request_count--;
                __zcrypt_increase_preference(zdev);
                put_device(&zdev->ap_dev->device);
@@ -373,14 +373,14 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
                get_device(&zdev->ap_dev->device);
                zdev->request_count++;
                __zcrypt_decrease_preference(zdev);
-               spin_unlock_bh(&zcrypt_device_lock);
                if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+                       spin_unlock_bh(&zcrypt_device_lock);
                        rc = zdev->ops->rsa_modexpo_crt(zdev, crt);
+                       spin_lock_bh(&zcrypt_device_lock);
                        module_put(zdev->ap_dev->drv->driver.owner);
                }
                else
                        rc = -EAGAIN;
-               spin_lock_bh(&zcrypt_device_lock);
                zdev->request_count--;
                __zcrypt_increase_preference(zdev);
                put_device(&zdev->ap_dev->device);
@@ -408,14 +408,14 @@ static long zcrypt_send_cprb(struct ica_xcRB *xcRB)
                get_device(&zdev->ap_dev->device);
                zdev->request_count++;
                __zcrypt_decrease_preference(zdev);
-               spin_unlock_bh(&zcrypt_device_lock);
                if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+                       spin_unlock_bh(&zcrypt_device_lock);
                        rc = zdev->ops->send_cprb(zdev, xcRB);
+                       spin_lock_bh(&zcrypt_device_lock);
                        module_put(zdev->ap_dev->drv->driver.owner);
                }
                else
                        rc = -EAGAIN;
-               spin_lock_bh(&zcrypt_device_lock);
                zdev->request_count--;
                __zcrypt_increase_preference(zdev);
                put_device(&zdev->ap_dev->device);