linux-kernel - Re: [PATCH v2] perf callchain: Compare dsos (as well) for CCKEY

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Date:   Thu, 5 Oct 2017 11:26:43 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
Cc:     pozdneyev@...il.com, acme@...nel.org, linux-kernel@...r.kernel.org,
        jolsa@...nel.org, namhyung@...nel.org,
        linux-perf-users@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        yao.jin@...ux.intel.com, ak@...ux.intel.com,
        kjlx@...pleofstupid.com, milian.wolff@...b.com,
        zhangmengting@...wei.com
Subject: Re: [PATCH v2] perf callchain: Compare dsos (as well) for
 CCKEY_FUNCTION

On Thu, Oct 05, 2017 at 02:42:34PM +0530, Ravi Bangoria wrote:
> Two functions from different binaries can have same start
> address. Thus, comparing only start address in match_chain()
> leads to inconsistent callchains. Fix this by adding a check
> for dsos as well.
> 
> Ex, https://www.spinics.net/lists/linux-perf-users/msg04067.html
> 
> Reported-by: Alexander Pozdneev <pozdneyev@...il.com>
> Signed-off-by: Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
> ---
> Changes in v2:
>   - Remove unnecessary checks for 'map'

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka

> 
>  tools/perf/util/callchain.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index be09d77..a971caf 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -685,6 +685,8 @@ static enum match_result match_chain(struct callchain_cursor_node *node,
>  {
>  	struct symbol *sym = node->sym;
>  	u64 left, right;
> +	struct dso *left_dso = NULL;
> +	struct dso *right_dso = NULL;
>  
>  	if (callchain_param.key == CCKEY_SRCLINE) {
>  		enum match_result match = match_chain_srcline(node, cnode);
> @@ -696,12 +698,14 @@ static enum match_result match_chain(struct callchain_cursor_node *node,
>  	if (cnode->ms.sym && sym && callchain_param.key == CCKEY_FUNCTION) {
>  		left = cnode->ms.sym->start;
>  		right = sym->start;
> +		left_dso = cnode->ms.map->dso;
> +		right_dso = node->map->dso;
>  	} else {
>  		left = cnode->ip;
>  		right = node->ip;
>  	}
>  
> -	if (left == right) {
> +	if (left == right && left_dso == right_dso) {
>  		if (node->branch) {
>  			cnode->branch_count++;
>  
> -- 
> 1.8.3.1
>