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

[Jia-Ju Bai]

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