Re: [for-next][PATCH 13/23] USB: mtu3: tracing: Use the new __vstring() helper

[Chunfeng Yun <chunfeng.yun@mediatek.com>]

On Fri, 2022-07-15 at 17:24 -0400, Steven Rostedt wrote:
> On Fri, 15 Jul 2022 18:01:44 +0800
> Chunfeng Yun <chunfeng.yun@mediatek.com> wrote:
> 
> >  irq/254-1120100-137     [000] d..1.   266.629662: mtu3_log:
> > 11201000.usb: ep0_state SETUPr-speed
> > 
> > "r-speed" seems the remain of last log;
> 
> I found an off-by-one bug in the vstring patch. I'll rebase, test and
> try
> again.
> 
> In the mean time, care to add this on top to make sure it's fixed?
> 
> Thanks!
> 
> -- Steve
> 
> diff --git a/include/linux/trace_events.h
> b/include/linux/trace_events.h
> index e6f8ba52a958..b18759a673c6 100644
> --- a/include/linux/trace_events.h
> +++ b/include/linux/trace_events.h
> @@ -922,16 +922,16 @@ perf_trace_buf_submit(void *raw_data, int size,
> int rctx, u16 type,
>   * gcc warns that you can not use a va_list in an inlined
>   * function. But lets me make it into a macro :-/
>   */
> -#define __trace_event_vstr_len(fmt, va)		\
> -({						\
> -	va_list __ap;				\
> -	int __ret;				\
> -						\
> -	va_copy(__ap, *(va));			\
> -	__ret = vsnprintf(NULL, 0, fmt, __ap);	\
> -	va_end(__ap);				\
> -						\
> -	min(__ret, TRACE_EVENT_STR_MAX);	\
> +#define __trace_event_vstr_len(fmt, va)			\
> +({							\
> +	va_list __ap;					\
> +	int __ret;					\
> +							\
> +	va_copy(__ap, *(va));				\
> +	__ret = vsnprintf(NULL, 0, fmt, __ap) + 1;	\

It works fine now, thanks a lot

> +	va_end(__ap);					\
> +							\
> +	min(__ret, TRACE_EVENT_STR_MAX);		\
>  })
>  
>  #endif /* _LINUX_TRACE_EVENT_H */