Re: [PATCH v3] staging: vt6655: check for memory allocation failures

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On 2018/3/30 11:39, Ji-Hun Kim wrote:
On Fri, Mar 30, 2018 at 11:15:03AM +0800, Jia-Ju Bai wrote:

On 2018/3/30 10:44, Ji-Hun Kim wrote:
@@ -1165,10 +1205,18 @@ static int vnt_start(struct ieee80211_hw *hw)
  	}
  	dev_dbg(&priv->pcid->dev, "call device init rd0 ring\n");
-	device_init_rd0_ring(priv);
-	device_init_rd1_ring(priv);
-	device_init_td0_ring(priv);
-	device_init_td1_ring(priv);
+	ret = device_init_rd0_ring(priv);
+	if (ret)
+		goto error;
+	ret = device_init_rd1_ring(priv);
+	if (ret)
+		goto error;
+	ret = device_init_td0_ring(priv);
+	if (ret)
+		goto error;
+	ret = device_init_td1_ring(priv);
+	if (ret)
+		goto error;
  	device_init_registers(priv);
@@ -1178,6 +1226,8 @@ static int vnt_start(struct ieee80211_hw *hw)
  	ieee80211_wake_queues(hw);
  	return 0;
+error:
+	return ret;
  }
This code will lead to memory leaks when device_init_rd1_ring()
fails, because the memory allocated by device_init_rd0_ring() is not
freed.

I think this one will be better:
     ret = device_init_rd0_ring(priv);
     if (ret)
         goto error_init_rd0_ring;
     ret = device_init_rd1_ring(priv);
     if (ret)
         goto error_init_rd1_ring;
     ret = device_init_td0_ring(priv);
     if (ret)
         goto error_init_td0_ring;
     ret = device_init_td1_ring(priv);
     if (ret)
         goto error_init_td1_ring;
     ......
error_init_td1_ring:
     device_free_td0_ring(priv);
error_init_td0_ring:
     device_free_rd1_ring(priv);
error_init_rd1_ring:
     device_free_rd0_ring(priv);
error_init_rd0_ring:
     return ret;


Best wishes,
Jia-Ju Bai


But, those freeing function are already placed in the each device_init
functions for allocation fail like below.

I think it is okay.
I suppose that, for each device_init function, you only free the resources allocated in this function, and do not handle the resources in other functions.

@@ -550,20 +554,29 @@ static void device_init_rd0_ring(struct vnt_private *priv)
+       return 0;
+error:
+       device_free_rd0_ring(priv);
+       return ret;

This code is needed to free the resources allocated in this function.


Best wishes,
Jia-Ju Bai
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