tracing: add comment for use of double __builtin_consant_p
Impact: documentation The use of the double __builtin_contant_p checks in the event_trace_printk can be confusing to developers and reviewers. This patch adds a comment to explain why it is there. Requested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> LKML-Reference: <20090313122235.43EB.A69D9226@jp.fujitsu.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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@ -776,6 +776,11 @@ extern struct ftrace_event_call __stop_ftrace_events[];
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extern const char *__start___trace_bprintk_fmt[];
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extern const char *__stop___trace_bprintk_fmt[];
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/*
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* The double __builtin_constant_p is because gcc will give us an error
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* if we try to allocate the static variable to fmt if it is not a
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* constant. Even with the outer if statement optimizing out.
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*/
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#define event_trace_printk(ip, fmt, args...) \
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do { \
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__trace_printk_check_format(fmt, ##args); \
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