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SubjectRe: [PATCH] tracing/x86/xen: Remove zero data size trace events trace_xen_mmu_flush_tlb{_all}
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 <>


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