Messages in this thread | | | Date | Mon, 3 Mar 2014 14:51:10 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH 1/3] tracing: correctly expand len expressions from __dynamic_array macro |
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On Fri, 28 Feb 2014 21:32:16 -0800 Filipe Brandenburger <filbranden@google.com> wrote:
> This fixes expansion of the len argument in __dynamic_array macros. > The previous code from commit 7d536cb3f would not fully evaluate the > expression before multiplying its result by the size of the type. > > This went unnoticed because the length stored in the high 16 bits of the > offset (which is the one that was broken here) is only used by > filter_pred_strloc which only acts on strings for which the size of the > type is 1. >
Was this visible in any of the tracepoints? Should this be marked for stable? It's been in the kernel for a long time (2009). Or is a new tracepoint showing a problem?
-- Steve
> Signed-off-by: Filipe Brandenburger <filbranden@google.com> > --- > include/trace/ftrace.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h > index 1a8b28d..82e8d89 100644 > --- a/include/trace/ftrace.h > +++ b/include/trace/ftrace.h > @@ -375,7 +375,7 @@ ftrace_define_fields_##call(struct ftrace_event_call *event_call) \ > #define __dynamic_array(type, item, len) \ > __data_offsets->item = __data_size + \ > offsetof(typeof(*entry), __data); \ > - __data_offsets->item |= (len * sizeof(type)) << 16; \ > + __data_offsets->item |= ((len) * sizeof(type)) << 16; \ > __data_size += (len) * sizeof(type); > > #undef __string
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