Re: [RFC patch 2/5] trace event skb fix unassigned field

[Frederic Weisbecker]

On Tue, Jan 04, 2011 at 06:46:06PM -0500, nhorman@xxxxxxxxxxxxx wrote:
> Acked- by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> 
> 
> Sent from my Verizon Wireless Phone
> 
> ----- Reply message -----
> From: "Mathieu Desnoyers" <mathieu.desnoyers@xxxxxxxxxxxx>
> Date: Tue, Jan 4, 2011 6:16 pm
> Subject: [RFC patch 2/5] trace event skb fix unassigned field
> To: "LKML" <linux-kernel@xxxxxxxxxxxxxxx>
> Cc: "Mathieu Desnoyers" <mathieu.desnoyers@xxxxxxxxxxxx>, "Steven Rostedt" <rostedt@xxxxxxxxxxx>, "Frederic Weisbecker" <fweisbec@xxxxxxxxx>, "Ingo Molnar" <mingo@xxxxxxx>, "Neil Horman" <nhorman@xxxxxxxxxxxxx>, "Thomas Gleixner" <tglx@xxxxxxxxxxxxx>
> 
> 
> The field "protocol" in event kfree_skb is left unassigned if skb is NULL,
> leaving its trace output as garbage. Assign the value to 0 when skb is NULL
> instead.

Hm, if the skb is already null, we probably shouldn't send any trace.

What about using TP_CONDITION() ?

> 
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
> CC: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> CC: Ingo Molnar <mingo@xxxxxxx>
> CC: Neil Horman <nhorman@xxxxxxxxxxxxx>
> CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
>  include/trace/events/skb.h |    4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> Index: linux-2.6-lttng/include/trace/events/skb.h
> ===================================================================
> --- linux-2.6-lttng.orig/include/trace/events/skb.h
> +++ linux-2.6-lttng/include/trace/events/skb.h
> @@ -25,9 +25,7 @@ TRACE_EVENT(kfree_skb,
>  
>  	TP_fast_assign(
>  		__entry->skbaddr = skb;
> -		if (skb) {
> -			__entry->protocol = ntohs(skb->protocol);
> -		}
> +		__entry->protocol = skb ? ntohs(skb->protocol) : 0;
>  		__entry->location = location;
>  	),
>  
> 
> 
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