Hi,

On Thu, Oct 05, 2017 at 09:20:21AM +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 <[email protected]>
> Signed-off-by: Ravi Bangoria <[email protected]>
> ---
>  tools/perf/util/callchain.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index be09d77..6d7f645 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -685,6 +685,9 @@ 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 +699,16 @@ 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;
> +             if (cnode->ms.map)
> +                     left_dso = cnode->ms.map->dso;
> +             if (node->map)
> +                     right_dso = node->map->dso;

AFAIK having a symbol guarantees having a map too.  So it could simply
be:

                left_dso = cnode->ms.map->dso;
                right_dso = node->map->dso;

Thanks,
Namhyung


>       } 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
> 
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