Re: [PATCH v2] nbd: Fix NULL pointer in flush_workqueue

[Sun Ke <sunke32@xxxxxxxxxx>]

hi，Markus

在 2021/2/2 3:05, Markus Elfring 写道:
> …
> > +++ b/drivers/block/nbd.c
> > @@ -2011,12 +2011,14 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
> >   		       index);
> >   		return -EINVAL;
> >   	}
> > +	mutex_lock(&nbd->config_lock);
> >   	if (!refcount_inc_not_zero(&nbd->refs)) {
> > -		mutex_unlock(&nbd_index_mutex);
> > -		printk(KERN_ERR "nbd: device at index %d is going down\n",
> > -		       index);
> > -		return -EINVAL;
> > +		goto unlock;
> >   	}
> > +	if (!nbd->recv_workq) {
> > +		goto unlock;
> > +	}
> How do you think about to use the following patch variant
> (so that unwanted curly brackets would be avoided for proposed single statements
> in two if branches)?
>
> +	mutex_lock(&nbd->config_lock);
> -	if (!refcount_inc_not_zero(&nbd->refs)) {
> +	if (!refcount_inc_not_zero(&nbd->refs) || !nbd->recv_workq) {
> +		mutex_unlock(&nbd->config_lock);
>   		mutex_unlock(&nbd_index_mutex);
>   		printk(KERN_ERR "nbd: device at index %d is going down\n",tter
>   		       index);
>   		return -EINVAL;
>   	}
It looks better,  thanks for your suggestion.
> By the way:
> Would you like to replace the following two statements by the statement
> “goto put_nbd;” in another update step for this function implementation?
>
> 		nbd_put(nbd);
> 		return 0;
Sure, I will do it.
> Regards,
> Markus

Thanks,

Sun Ke

> .