Re: [PATCH v5 06/21] perf arm-spe: Refactor printing string to buffer

[Leo Yan]

On Thu, Oct 29, 2020 at 10:54:37AM +0000, André Przywara wrote:
> On 29/10/2020 10:51, Leo Yan wrote:
> > Hi Andre,
> > 
> > On Thu, Oct 29, 2020 at 10:23:39AM +0000, Andr� Przywara wrote:
> > 
> > [...]
> > 
> >>> +static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> >>> +				const char *fmt, ...)
> >>> +{
> >>> +	va_list ap;
> >>> +	int ret;
> >>> +
> >>> +	va_start(ap, fmt);
> >>> +	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> >>> +	va_end(ap);
> >>> +
> >>> +	if (ret < 0) {
> >>> +		if (err && !*err)
> >>> +			*err = ret;
> >>> +	} else {
> >>> +		*buf_p += ret;
> >>> +		*blen -= ret;
> >>> +	}
> >>> +
> >>> +	return ret;
> >>> +}
> >>
> >> So this now implements the old behaviour of ignoring previous errors, in
> >> all cases, since we don't check for errors and bail out in the callers.
> >>
> >> If you simply check for validity of err and for it being 0 before
> >> proceeding with the va_start() above, this should be fixed.
> > 
> > I think you are suggesting below code, could you take a look for it
> > before I proceed to respin new patch?>
> > static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> > 				const char *fmt, ...)
> > {
> > 	va_list ap;
> > 	int ret;
> > 
> >         /* Bail out if any error occurred */
> >         if (err && *err)
> >                 return *err;
> > 
> > 	va_start(ap, fmt);
> > 	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> > 	va_end(ap);
> > 
> > 	if (ret < 0) {
> > 		if (err && !*err)
> > 			*err = ret;
> > 	} else {
> > 		*buf_p += ret;
> > 		*blen -= ret;
> > 	}
> > 
> > 	return ret;
> > }
> 
> Yes, this is what I had in mind.

Thanks for confirmation, Andre.

Leo