linux-kernel - Re: [PATCH V3 2/3] perf tool: Move cpumode resolve code to add_callchain

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Date:	Mon, 17 Nov 2014 15:00:43 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	kan.liang@...el.com
Cc:	acme@...nel.org, a.p.zijlstra@...llo.nl, eranian@...gle.com,
	linux-kernel@...r.kernel.org, mingo@...hat.com, paulus@...ba.org,
	ak@...ux.intel.com
Subject: Re: [PATCH V3 2/3] perf tool: Move cpumode resolve code to
 add_callchain_ip

On Fri, Nov 14, 2014 at 08:44:11AM -0500, kan.liang@...el.com wrote:

SNIP

> -	int i;
> -	int j;
> -	int err;
> +	int i, j, err = 0;
>  	int skip_idx __maybe_unused;
>  
>  	callchain_cursor_reset(&callchain_cursor);
> @@ -1467,39 +1489,13 @@ static int thread__resolve_callchain_sample(struct thread *thread,
>  #endif
>  		ip = chain->ips[j];
>  
> -		if (ip >= PERF_CONTEXT_MAX) {
> -			switch (ip) {
> -			case PERF_CONTEXT_HV:
> -				cpumode = PERF_RECORD_MISC_HYPERVISOR;
> -				break;
> -			case PERF_CONTEXT_KERNEL:
> -				cpumode = PERF_RECORD_MISC_KERNEL;
> -				break;
> -			case PERF_CONTEXT_USER:
> -				cpumode = PERF_RECORD_MISC_USER;
> -				break;
> -			default:
> -				pr_debug("invalid callchain context: "
> -					 "%"PRId64"\n", (s64) ip);
> -				/*
> -				 * It seems the callchain is corrupted.
> -				 * Discard all.
> -				 */
> -				callchain_cursor_reset(&callchain_cursor);
> -				return 0;
> -			}
> -			continue;
> -		}
> -
>  		err = add_callchain_ip(thread, parent, root_al,
>  				       cpumode, ip);
> -		if (err == -EINVAL)
> -			break;

yea, I was wondering, why we did not spot this nop before ;-)

>  		if (err)
> -			return err;
> +			goto exit;

I dont understand this change seems like extra nop complication..
why not return in here and rather recheck at the end again?

jirka

>  	}
> -
> -	return 0;
> +exit:
> +	return (err < 0) ? err : 0;
>  }
--
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