netdev - Re: [PATCH] ftrace: tracepoint of net_dev_xmit sees freed skb and causes panic

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Message-ID: <1306858890.11899.32.camel@gandalf.stny.rr.com>
Date:	Tue, 31 May 2011 12:21:30 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Neil Horman <nhorman@...driver.com>
Cc:	Koki Sanagi <sanagi.koki@...fujitsu.com>,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	davem@...emloft.net, mingo@...e.hu, fweisbec@...il.com,
	mathieu.desnoyers@...icios.com, tglx@...utronix.de,
	kosaki.motohiro@...fujitsu.com, izumi.taku@...fujitsu.com,
	kaneshige.kenji@...fujitsu.com
Subject: Re: [PATCH] ftrace: tracepoint of net_dev_xmit sees freed skb and
 causes panic

On Tue, 2011-05-31 at 12:11 -0400, Neil Horman wrote:
>  			skb_dst_drop(nskb);
> > >  
> > > +		skb_len = nskb->len;
> > >  		rc = ops->ndo_start_xmit(nskb, dev);
> > > -		trace_net_dev_xmit(nskb, rc);
> > > +		trace_net_dev_xmit(nskb, rc, dev, skb_len);
> > 
> > What if you just put the tracepoint before the call to
> > ops->ndo_start_xmit?
> > 
> Then you won't know the return code of ndo_start_xmit, which this tracepoint
> records.

Doh! Yeah, I see that now ;)

-- Steve


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