linux-kernel - Re: [PATCH net] net: stmmac: free an skb first when there are no longer any descriptors using it

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Date:   Tue, 20 Jun 2017 15:41:23 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     niklas.cassel@...s.com
Cc:     peppe.cavallaro@...com, alexandre.torgue@...com, niklass@...s.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: stmmac: free an skb first when there are no
 longer any descriptors using it

From: Niklas Cassel <niklas.cassel@...s.com>
Date: Tue, 20 Jun 2017 14:32:41 +0200

> When having the skb pointer in the first descriptor, stmmac_tx_clean
> can get called at a moment where the IP has only cleared the own bit
> of the first descriptor, thus freeing the skb, even though there can
> be several descriptors whose buffers point into the same skb.
> 
> By simply moving the skb pointer from the first descriptor to the last
> descriptor, a skb will get freed only when the IP has cleared the
> own bit of all the descriptors that are using that skb.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>

Applied and queued up for -stable, thanks.