crypto: qat - fix concurrency issue when device state changes

The sysfs `state` attribute is not protected against race conditions.
If multiple processes perform a device state transition on the same
device in parallel, unexpected behaviors might occur.

For transitioning the device state, adf_sysfs.c calls the functions
adf_dev_init(), adf_dev_start(), adf_dev_stop() and adf_dev_shutdown()
which are unprotected and interdependent on each other. To perform a
state transition, these functions needs to be called in a specific
order:
  * device up:   adf_dev_init() -> adf_dev_start()
  * device down: adf_dev_stop() -> adf_dev_shutdown()

This change introduces the functions adf_dev_up() and adf_dev_down()
which wrap the state machine functions and protect them with a
per-device lock. These are then used in adf_sysfs.c instead of the
individual state transition functions.

Fixes: 5ee52118ac ("crypto: qat - expose device state through sysfs for 4xxx")
Signed-off-by: Shashank Gupta <shashank.gupta@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/qat/qat_common/adf_accel_devices.h

@@ -310,6 +310,7 @@ struct adf_accel_dev {
 			u8 pf_compat_ver;
 		} vf;
 	};
+	struct mutex state_lock; /* protect state of the device */
 	bool is_vf;
 	u32 accel_id;
 };

drivers/crypto/qat/qat_common/adf_common_drv.h

@@ -58,6 +58,9 @@ void adf_dev_stop(struct adf_accel_dev *accel_dev);
 void adf_dev_shutdown(struct adf_accel_dev *accel_dev);
 int adf_dev_shutdown_cache_cfg(struct adf_accel_dev *accel_dev);
 
+int adf_dev_up(struct adf_accel_dev *accel_dev, bool init_config);
+int adf_dev_down(struct adf_accel_dev *accel_dev, bool cache_config);
+
 void adf_devmgr_update_class_index(struct adf_hw_device_data *hw_data);
 void adf_clean_vf_map(bool);
 

drivers/crypto/qat/qat_common/adf_dev_mgr.c

@@ -223,6 +223,7 @@ int adf_devmgr_add_dev(struct adf_accel_dev *accel_dev,
 		map->attached = true;
 		list_add_tail(&map->list, &vfs_table);
 	}
+	mutex_init(&accel_dev->state_lock);
 unlock:
 	mutex_unlock(&table_lock);
 	return ret;
@@ -269,6 +270,7 @@ void adf_devmgr_rm_dev(struct adf_accel_dev *accel_dev,
 		}
 	}
 unlock:
+	mutex_destroy(&accel_dev->state_lock);
 	list_del(&accel_dev->list);
 	mutex_unlock(&table_lock);
 }

drivers/crypto/qat/qat_common/adf_init.c

@@ -400,3 +400,67 @@ int adf_dev_shutdown_cache_cfg(struct adf_accel_dev *accel_dev)
 
 	return 0;
 }
+
+int adf_dev_down(struct adf_accel_dev *accel_dev, bool reconfig)
+{
+	int ret = 0;
+
+	if (!accel_dev)
+		return -EINVAL;
+
+	mutex_lock(&accel_dev->state_lock);
+
+	if (!adf_dev_started(accel_dev)) {
+		dev_info(&GET_DEV(accel_dev), "Device qat_dev%d already down\n",
+			 accel_dev->accel_id);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (reconfig) {
+		ret = adf_dev_shutdown_cache_cfg(accel_dev);
+		goto out;
+	}
+
+	adf_dev_stop(accel_dev);
+	adf_dev_shutdown(accel_dev);
+
+out:
+	mutex_unlock(&accel_dev->state_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adf_dev_down);
+
+int adf_dev_up(struct adf_accel_dev *accel_dev, bool config)
+{
+	int ret = 0;
+
+	if (!accel_dev)
+		return -EINVAL;
+
+	mutex_lock(&accel_dev->state_lock);
+
+	if (adf_dev_started(accel_dev)) {
+		dev_info(&GET_DEV(accel_dev), "Device qat_dev%d already up\n",
+			 accel_dev->accel_id);
+		ret = -EALREADY;
+		goto out;
+	}
+
+	if (config && GET_HW_DATA(accel_dev)->dev_config) {
+		ret = GET_HW_DATA(accel_dev)->dev_config(accel_dev);
+		if (unlikely(ret))
+			goto out;
+	}
+
+	ret = adf_dev_init(accel_dev);
+	if (unlikely(ret))
+		goto out;
+
+	ret = adf_dev_start(accel_dev);
+
+out:
+	mutex_unlock(&accel_dev->state_lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adf_dev_up);

drivers/crypto/qat/qat_common/adf_sysfs.c

@@ -50,38 +50,21 @@ static ssize_t state_store(struct device *dev, struct device_attribute *attr,
 
 	switch (ret) {
 	case DEV_DOWN:
-		if (!adf_dev_started(accel_dev)) {
-			dev_info(dev, "Device qat_dev%d already down\n",
-				 accel_id);
-			return -EINVAL;
-		}
-
 		dev_info(dev, "Stopping device qat_dev%d\n", accel_id);
 
-		ret = adf_dev_shutdown_cache_cfg(accel_dev);
+		ret = adf_dev_down(accel_dev, true);
 		if (ret < 0)
 			return -EINVAL;
 
 		break;
 	case DEV_UP:
-		if (adf_dev_started(accel_dev)) {
-			dev_info(dev, "Device qat_dev%d already up\n",
-				 accel_id);
-			return -EINVAL;
-		}
-
 		dev_info(dev, "Starting device qat_dev%d\n", accel_id);
 
-		ret = GET_HW_DATA(accel_dev)->dev_config(accel_dev);
+		ret = adf_dev_up(accel_dev, true);
-		if (!ret)
-			ret = adf_dev_init(accel_dev);
-		if (!ret)
-			ret = adf_dev_start(accel_dev);
-
 		if (ret < 0) {
 			dev_err(dev, "Failed to start device qat_dev%d\n",
 				accel_id);
-			adf_dev_shutdown_cache_cfg(accel_dev);
+			adf_dev_down(accel_dev, true);
 			return ret;
 		}
 		break;