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Commit bdc06758 authored by Steven Rostedt's avatar Steven Rostedt
Browse files

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: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20090313122235.43EB.A69D9226@jp.fujitsu.com>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
parent eb1871f3

kernel/trace/trace.h

+5 −0
Original line number Diff line number Diff line
@@ -776,6 +776,11 @@ extern struct ftrace_event_call __stop_ftrace_events[]; 
extern const char *__start___trace_bprintk_fmt[];

extern const char *__stop___trace_bprintk_fmt[];



/*

 * The double __builtin_constant_p is because gcc will give us an error

 * if we try to allocate the static variable to fmt if it is not a

 * constant. Even with the outer if statement optimizing out.

 */

#define event_trace_printk(ip, fmt, args...)				\

do {									\

	__trace_printk_check_format(fmt, ##args);			\