Date: Mon, 11 May 2015 10:59:38 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: He Kuang <hekuang@huawei.com>
Cc: masami.hiramatsu.pt@hitachi.com, a.p.zijlstra@chello.nl, jolsa@kernel.org,
        mingo@redhat.com, wangnan0@huawei.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 3/3] perf probe: Show better error message when failed
 to find variable
Message-ID: <20150511135938.GH28183@kernel.org>
References: <1431349804-31849-1-git-send-email-hekuang@huawei.com>
 <1431349804-31849-3-git-send-email-hekuang@huawei.com>
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Em Mon, May 11, 2015 at 01:10:04PM +0000, He Kuang escreveu:
> Indicate to check variable location range in error message when we got
> failed to find the variable, and put user-supplied variable name in
> quotes.
> 
> Before this patch:
> 
>   $ perf probe --add 'generic_perform_write+118 bytes'
>   Failed to find the location of bytes at this address.
>    Perhaps, it has been optimized out.
>     Error: Failed to add events.
> 
> After this patch:
>   $ perf probe --add 'generic_perform_write+118 bytes'
>   Failed to find the location of the 'bytes' variable at this address.
>    Perhaps, it has been optimized out.
>    Use -V with --range option to show variable location range.
>     Error: Failed to add events.

See my other reply.

- Arnaldo
 
> Signed-off-by: He Kuang <hekuang@huawei.com>
> ---
>  tools/perf/util/probe-finder.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index f032329..0fc2ae8 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -528,8 +528,10 @@ static int convert_variable(Dwarf_Die *vr_die, struct probe_finder *pf)
>  	ret = convert_variable_location(vr_die, pf->addr, pf->fb_ops,
>  					&pf->sp_die, pf->tvar);
>  	if (ret == -ENOENT || ret == -EINVAL)
> -		pr_err("Failed to find the location of %s at this address.\n"
> -		       " Perhaps, it has been optimized out.\n", pf->pvar->var);
> +		pr_err("Failed to find the location of the '%s' variable at this address.\n"
> +		       " Perhaps, it has been optimized out.\n"
> +		       " Use -V with --range option to show variable location range.\n",
> +		       pf->pvar->var);
>  	else if (ret == -ENOTSUP)
>  		pr_err("Sorry, we don't support this variable location yet.\n");
>  	else if (ret == 0 && pf->pvar->field) {
> -- 
> 1.8.5.2
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