linux-kernel - Re: [PATCH v3 3/5] tracing: Add method for recording "func

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Date:   Tue, 13 Apr 2021 14:24:31 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Yordan Karadzhov (VMware)" <y.karadz@...il.com>
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        peterz@...radead.org
Subject: Re: [PATCH v3 3/5] tracing: Add method for recording "func_repeats"
 events

On Fri,  9 Apr 2021 21:10:29 +0300
"Yordan Karadzhov (VMware)" <y.karadz@...il.com> wrote:

> @@ -342,6 +342,12 @@ FTRACE_ENTRY(hwlat, hwlat_entry,
>  #define FUNC_REPEATS_GET_DELTA_TS(entry)			\
>  (((u64)entry->top_delta_ts << 32) | entry->bottom_delta_ts)	\
>  
> +#define FUNC_REPEATS_SET_DELTA_TS(entry, delta)			\
> +	do {							\
> +		entry->bottom_delta_ts = delta & U32_MAX;	\
> +		entry->top_delta_ts = (delta >> 32);		\
> +	} while (0);						\
> +

This needs the parenthesis around the parameters as well.

Or just make it into a static inline function. The GET_DELTA_TS is used in
printing to of the event for user space where it makes sense to have it as
a macro (it will be expanded in the "print fmt" of the format file for the
event). But the setting doesn't have that limitation.

static inline void
func_repeats_set_delta_ts(struct func_repeats_entry *entry,
			  unsigned long long delta)
{
	entry->bottom_delta_ts = delta & U32_MAX;
	entry->top_delta_ts = (delta >> 32);
}

And then you can have the compiler type check everything for you. Macros
are nasty when it comes to build errors.

-- Steve


>  FTRACE_ENTRY(func_repeats, func_repeats_entry,
>  
>  	TRACE_FUNC_REPEATS,
> --