linux-kernel - Re: [PATCH 2/4] perf-probe: Fix wrong variable warning when the probe point is not found

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Message-ID: <20200710111601.GL874@linux.vnet.ibm.com>
Date:   Fri, 10 Jul 2020 16:46:01 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Oleg Nesterov <oleg@...hat.com>, linux-kernel@...r.kernel.org,
        Andi Kleen <andi@...stfloor.org>,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/4] perf-probe: Fix wrong variable warning when the
 probe point is not found

* Masami Hiramatsu <mhiramat@...nel.org> [2020-07-09 17:07:12]:

> Fix a wrong "variable not found" warning when the probe point is
> not found in the debuginfo.
> Since the debuginfo__find_probes() can return 0 even if it does not
> find given probe point in the debuginfo, fill_empty_trace_arg() can
> be called with tf.ntevs == 0 and it can warn a wrong warning.
> To fix this, reject ntevs == 0 in fill_empty_trace_arg().
> 
> 
> 
> Reported-by: Andi Kleen <andi@...stfloor.org>
> Fixes: cb4027308570 ("perf probe: Trace a magic number if variable is not found")
> Cc: stable@...r.kernel.org
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>

Looks good to me.

Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

> ---
>  tools/perf/util/probe-finder.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
> index 55924255c535..9963e4e8ea20 100644
> --- a/tools/perf/util/probe-finder.c
> +++ b/tools/perf/util/probe-finder.c
> @@ -1408,6 +1408,9 @@ static int fill_empty_trace_arg(struct perf_probe_event *pev,
>  	char *type;
>  	int i, j, ret;
> 
> +	if (!ntevs)
> +		return -ENOENT;
> +
>  	for (i = 0; i < pev->nargs; i++) {
>  		type = NULL;
>  		for (j = 0; j < ntevs; j++) {
> 

-- 
Thanks and Regards
Srikar Dronamraju