linux-kernel - Re: [PATCH perf/core 01/13] perf probe: Fix to free temporal Dwarf

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Date:	Thu, 19 Nov 2015 08:32:19 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org,
	Adrian Hunter <adrian.hunter@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH perf/core 01/13] perf probe: Fix to free temporal Dwarf_Frame

On November 19, 2015 7:36:39 AM GMT+09:00, Arnaldo Carvalho de Melo <acme@...nel.org> wrote:
>Em Wed, Nov 18, 2015 at 03:40:12PM +0900, Masami Hiramatsu escreveu:
>> Since dwarf_cfi_addrframe returns malloc'd Dwarf_Frame
>> object, it has to be freed after used.
>
>Applied to perf/urgent
> 
>> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
>> ---
>>  tools/perf/util/probe-finder.c |    9 ++++++---
>>  1 file changed, 6 insertions(+), 3 deletions(-)
>> 
>> diff --git a/tools/perf/util/probe-finder.c
>b/tools/perf/util/probe-finder.c
>> index 63993d7..4d7d4f4 100644
>> --- a/tools/perf/util/probe-finder.c
>> +++ b/tools/perf/util/probe-finder.c
>> @@ -683,21 +683,24 @@ static int call_probe_finder(Dwarf_Die *sc_die,
>struct probe_finder *pf)
>>  	ret = dwarf_getlocation_addr(&fb_attr, pf->addr, &pf->fb_ops,
>&nops, 1);
>>  	if (ret <= 0 || nops == 0) {
>>  		pf->fb_ops = NULL;
>> +		ret = 0;
>>  #if _ELFUTILS_PREREQ(0, 142)
>>  	} else if (nops == 1 && pf->fb_ops[0].atom == DW_OP_call_frame_cfa
>&&
>>  		   pf->cfi != NULL) {
>> -		Dwarf_Frame *frame;
>> +		Dwarf_Frame *frame = NULL;
>>  		if (dwarf_cfi_addrframe(pf->cfi, pf->addr, &frame) != 0 ||
>>  		    dwarf_frame_cfa(frame, &pf->fb_ops, &nops) != 0) {

What if dwarf_cfi_addrframe() succeeded but
dwarf_frame_cfa() failed?  It seems that the frame
still can be leaked..

Thanks
Namhyung


>>  			pr_warning("Failed to get call frame on 0x%jx\n",
>>  				   (uintmax_t)pf->addr);
>> -			return -ENOENT;
>> +			ret = -ENOENT;
>>  		}
>> +		free(frame);
>>  #endif
>>  	}
>>  
>>  	/* Call finder's callback handler */
>> -	ret = pf->callback(sc_die, pf);
>> +	if (ret >= 0)
>> +		ret = pf->callback(sc_die, pf);
>>  
>>  	/* *pf->fb_ops will be cached in libdw. Don't free it. */
>>  	pf->fb_ops = NULL;

Hi Arnaldo and Masami,
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.
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