netdev - Re: [PATCH] net: handle the return value of pskb_carve_frag

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Message-Id: <20200816.210101.1889351303629244050.davem@davemloft.net>
Date:   Sun, 16 Aug 2020 21:01:01 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     linmiaohe@...wei.com
Cc:     kuba@...nel.org, martin.varghese@...ia.com, fw@...len.de,
        pshelar@....org, dcaratti@...hat.com, edumazet@...gle.com,
        steffen.klassert@...unet.com, pabeni@...hat.com,
        shmulik@...anetworks.com, kyk.segfault@...il.com,
        sowmini.varadhan@...cle.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: handle the return value of pskb_carve_frag_list()
 correctly

From: linmiaohe <linmiaohe@...wei.com>
Date: Mon, 17 Aug 2020 02:27:23 +0000

> David Miller <davem@...emloft.net> wrote:
>>> +	/* split line is in frag list */
>>> +	if (k == 0 && pskb_carve_frag_list(skb, shinfo, off - pos, gfp_mask)) {
>>> +		/* skb_frag_unref() is not needed here as shinfo->nr_frags = 0. */
>>> +		if (skb_has_frag_list(skb))
>>> +			kfree_skb_list(skb_shinfo(skb)->frag_list);
>>> +		kfree(data);
>>> +		return -ENOMEM;
>>
>>On error, the caller is going to kfree_skb(skb) which will take care of the frag list.
>>
> 
> I'am sorry for my careless. The caller will take care of the frag list and kfree(data) is enough here.
> Many thanks for review, will send v2 soon.

Actually, reading this again, what about the skb_clone_fraglist() done a few
lines up?  Who will release that reference to the fraglist items?

Maybe the kfree_skb_list() is necessary after all?