Messages in this thread | | | Date | Wed, 5 Jan 2011 01:49:06 +0100 | From | Frederic Weisbecker <> | Subject | Re: [RFC patch 2/5] trace event skb fix unassigned field |
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On Tue, Jan 04, 2011 at 07:40:38PM -0500, Mathieu Desnoyers wrote: > * Frederic Weisbecker (fweisbec@gmail.com) wrote: > > On Tue, Jan 04, 2011 at 06:46:06PM -0500, nhorman@tuxdriver.com wrote: > > > Acked- by: Neil Horman <nhorman@tuxdriver.com> > > > > > > > > > Sent from my Verizon Wireless Phone > > > > > > ----- Reply message ----- > > > From: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com> > > > Date: Tue, Jan 4, 2011 6:16 pm > > > Subject: [RFC patch 2/5] trace event skb fix unassigned field > > > To: "LKML" <linux-kernel@vger.kernel.org> > > > Cc: "Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>, "Steven Rostedt" <rostedt@goodmis.org>, "Frederic Weisbecker" <fweisbec@gmail.com>, "Ingo Molnar" <mingo@elte.hu>, "Neil Horman" <nhorman@tuxdriver.com>, "Thomas Gleixner" <tglx@linutronix.de> > > > > > > > > > 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() ? > > Hrm, let's see. It's been introduced by commit > 5cb3d1d9d34ac04bcaa2034139345b2a5fea54c1 > by Zhaolei. > > Event at the time of that commit, the only caller looked like: > > void kfree_skb(struct sk_buff *skb) > { > if (unlikely(!skb)) > return; > if (likely(atomic_read(&skb->users) == 1)) > smp_rmb(); > else if (likely(!atomic_dec_and_test(&skb->users))) > return; > trace_kfree_skb(skb, __builtin_return_address(0)); > __kfree_skb(skb); > } > EXPORT_SYMBOL(kfree_skb); > > So it already checks for a null pointer before calling the tracepoint. This > leads me to wonder why why this check was added in the first place ?
Likely for no strong reasons :)
So I guess we can remove the check from the tracepoint?
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