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From: Juergen Gross <>
To: Steven Rostedt <>,
	LKML <>
Cc: Linus Torvalds <>,
	Andrew Morton <>,
	Ingo Molnar <>, "H. Peter Anvin" <>,
	Thomas Gleixner <>,
	Jingjie Jiang <>,
	Mukesh Rathor <>,
	Konrad Rzeszutek Wilk <>,
Subject: Re: [PATCH] tracing/x86/xen: Remove zero data size trace events trace_xen_mmu_flush_tlb{_all}
Date: Fri, 11 May 2018 06:14:07 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <20180509144605.5a220327@gandalf.local.home>

On 09/05/18 20:46, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <>
> Doing an audit of trace events, I discovered two trace events in the xen
> subsystem that use a hack to create zero data size trace events. This is not
> what trace events are for. Trace events add memory footprint overhead, and
> if all you need to do is see if a function is hit or not, simply make that
> function noinline and use function tracer filtering.
> Worse yet, the hack used was:
>  __array(char, x, 0)
> Which creates a static string of zero in length. There's assumptions about
> such constructs in ftrace that this is a dynamic string that is nul
> terminated. This is not the case with these tracepoints and can cause
> problems in various parts of ftrace.
> Nuke the trace events!
> Cc:
> Fixes: 95a7d76897c1e ("xen/mmu: Use Xen specific TLB flush instead of the generic one.")
> Signed-off-by: Steven Rostedt (VMware) <>

Any reason not sending this patch to the Xen maintainers?

I can take it through the Xen tree. :-)

Reviewed-by: Juergen Gross <>


  parent reply	other threads:[~2018-05-11  4:14 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-09 18:46 Steven Rostedt
2018-05-10 14:37 ` Steven Rostedt
2018-05-11  4:14 ` Juergen Gross [this message]
2018-05-11 13:12   ` Steven Rostedt
2018-05-14 20:29   ` Steven Rostedt

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