Thread (18 messages) 18 messages, 3 authors, 2019-09-24

Re: [PATCH v7 2/6] PM / devfreq: Move more initialization before registration

From: Chanwoo Choi <cw00.choi@samsung.com>
Date: 2019-09-24 02:53:04
Also in: linux-pm

Hi,

I'm not sure that it is necessary. Because, mainline kernel
provides the resource-managed feature with 'devm_*'
in order to reduce the memory leak by user.

It's like going back to a time when 'devm_*' feature wasn't there.
I think just it depends on the coding style of author.

I leave the final decision of this patch to Myungjoo.

On 19. 9. 24. 오전 6:10, Leonard Crestez wrote:
quoted hunk ↗ jump to hunk
In general it is a better to initialize an object before making it
accessible externally (through device_register).

This makes it possible to avoid relying on locking a partially
initialized object.

Signed-off-by: Leonard Crestez <redacted>
Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
---
 drivers/devfreq/devfreq.c | 43 +++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 18 deletions(-)
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index f5bea7350f72..8bbcd4efa09f 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -588,10 +588,12 @@ static void devfreq_dev_release(struct device *dev)
 	mutex_unlock(&devfreq_list_lock);
 
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
 
+	kfree(devfreq->time_in_state);
+	kfree(devfreq->trans_table);
 	mutex_destroy(&devfreq->lock);
 	kfree(devfreq);
 }
 
 /**
@@ -671,44 +673,43 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->max_freq = devfreq->scaling_max_freq;
 
 	devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
 	atomic_set(&devfreq->suspend_count, 0);
 
-	dev_set_name(&devfreq->dev, "devfreq%d",
-				atomic_inc_return(&devfreq_no));
-	err = device_register(&devfreq->dev);
-	if (err) {
-		mutex_unlock(&devfreq->lock);
-		put_device(&devfreq->dev);
-		goto err_out;
-	}
-
-	devfreq->trans_table = devm_kzalloc(&devfreq->dev,
+	devfreq->trans_table = kzalloc(
 			array3_size(sizeof(unsigned int),
 				    devfreq->profile->max_state,
 				    devfreq->profile->max_state),
 			GFP_KERNEL);
 	if (!devfreq->trans_table) {
 		mutex_unlock(&devfreq->lock);
 		err = -ENOMEM;
-		goto err_devfreq;
+		goto err_dev;
 	}
 
-	devfreq->time_in_state = devm_kcalloc(&devfreq->dev,
-			devfreq->profile->max_state,
-			sizeof(unsigned long),
-			GFP_KERNEL);
+	devfreq->time_in_state = kcalloc(devfreq->profile->max_state,
+					 sizeof(unsigned long),
+					 GFP_KERNEL);
 	if (!devfreq->time_in_state) {
 		mutex_unlock(&devfreq->lock);
 		err = -ENOMEM;
-		goto err_devfreq;
+		goto err_dev;
 	}
 
 	devfreq->last_stat_updated = jiffies;
 
 	srcu_init_notifier_head(&devfreq->transition_notifier_list);
 
+	dev_set_name(&devfreq->dev, "devfreq%d",
+				atomic_inc_return(&devfreq_no));
+	err = device_register(&devfreq->dev);
+	if (err) {
+		mutex_unlock(&devfreq->lock);
+		put_device(&devfreq->dev);
+		goto err_out;
+	}
+
 	mutex_unlock(&devfreq->lock);
 
 	mutex_lock(&devfreq_list_lock);
 
 	governor = try_then_request_governor(devfreq->governor_name);
@@ -734,14 +735,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	return devfreq;
 
 err_init:
 	mutex_unlock(&devfreq_list_lock);
-err_devfreq:
 	devfreq_remove_device(devfreq);
-	devfreq = NULL;
+	return ERR_PTR(err);
+
 err_dev:
+	/*
+	 * Cleanup path for errors that happen before registration.
+	 * Otherwise we rely on devfreq_dev_release.
+	 */
+	kfree(devfreq->time_in_state);
+	kfree(devfreq->trans_table);
 	kfree(devfreq);
 err_out:
 	return ERR_PTR(err);
 }
 EXPORT_SYMBOL(devfreq_add_device);

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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