Re: [PATCH v3] tools/lib/traceevent, perf tools: Handle %pU format correctly

[Qu Wenruo]

On 2019/10/21 äå9:56, Steven Rostedt wrote:
> On Mon, 21 Oct 2019 17:47:30 +0800
> Qu Wenruo <wqu@xxxxxxxx> wrote:
> 
>> +static void print_uuid_arg(struct trace_seq *s, void *data, int size,
>> +			   struct tep_event *event, struct tep_print_arg *arg)
>> +{
>> +	unsigned char *buf;
>> +	int i;
>> +
>> +	if (arg->type != TEP_PRINT_FIELD) {
>> +		trace_seq_printf(s, "ARG TYPE NOT FIELID but %d", arg->type);
>> +		return;
>> +	}
>> +
>> +	if (!arg->field.field) {
>> +		arg->field.field = tep_find_any_field(event, arg->field.name);
>> +		if (!arg->field.field) {
>> +			do_warning("%s: field %s not found",
>> +				   __func__, arg->field.name);
>> +			return;
>> +		}
>> +	}
>> +	if (arg->field.field->size < 16) {
>> +		trace_seq_printf(s, "INVALID UUID: size have %u expect 16",
>> +				arg->field.field->size);
>> +		return;
>> +	}
>> +	buf = data + arg->field.field->offset;
>> +
>> +	for (i = 0; i < 8; i++) {
>> +		trace_seq_printf(s, "%02x", buf[2 * i]);
>> +		trace_seq_printf(s, "%02x", buf[2 * i + 1]);
>> +		if (1 <= i && i <= 4)
> 
> I'm fine with this patch except for one nit. The above is hard to read
> (in my opinion), and I absolutely hate the "constant" compare to
> "variable" notation. Please change the above to:
> 
> 		if (i >= 1 && i <= 4)

Isn't this ( 1 <= i && i <= 4 ) easier to find out the lower and upper
boundary? only two numbers, both at the end of the expression.

I feel that ( i >= 1 && i <= 4 ) easier to write, but takes me extra
half second to read, thus I changed to the current one.

Thanks,
Qu

> 
> Thanks,
> 
> -- Steve
> 
>> +			trace_seq_putc(s, '-');
>> +	}
>> +}
>> +

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