netdev - Re: [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with skb_cow

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Message-ID: <20201103093932.26cf1f0c@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Tue, 3 Nov 2020 09:39:32 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Claudiu Manoil <claudiu.manoil@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        "james.jurack@...tek.com" <james.jurack@...tek.com>
Subject: Re: [PATCH net v2 1/2] gianfar: Replace skb_realloc_headroom with
 skb_cow_head for PTP

On Tue, 3 Nov 2020 09:36:55 -0800 Jakub Kicinski wrote:
> On Tue, 3 Nov 2020 19:30:07 +0200 Vladimir Oltean wrote:
> > On Tue, Nov 03, 2020 at 05:18:25PM +0000, Claudiu Manoil wrote:  
> > > It's either the dev_kfree_skb_any from the dma mapping error path or the one
> > > from skb_cow_head()'s error path.  A confirmation would help indeed.    
> > 
> > It says "consume", not "kfree", which in my mind would make it point
> > towards the only caller of consume_skb from the gianfar driver, i.e. the
> > dev_consume_skb_any that you just added.  
> 
> #define dev_kfree_skb(a)	consume_skb(a)
> 
> IIRC we did this because too many drivers used dev_kfree_skb
> incorrectly and made the dropwatch output very noisy.

FWIW ./scripts/decode_stacktrace.sh should point you right to the lines
of code if the build has enough debug info.