Re: [PATCH v2 1/2]: perf util: map data buffer for preserving collected data

[Jiri Olsa]

On Thu, Aug 23, 2018 at 07:42:09PM +0300, Alexey Budankov wrote:

SNIP

> diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
> index fc832676a798..e71d46cb01cc 100644
> --- a/tools/perf/util/mmap.c
> +++ b/tools/perf/util/mmap.c
> @@ -155,6 +155,10 @@ void __weak auxtrace_mmap_params__set_idx(struct 
> auxtrace_mmap_params *mp __mayb
>  
>  void perf_mmap__munmap(struct perf_mmap *map)
>  {
> +     if (map->data != NULL) {
> +             munmap(map->data, perf_mmap__mmap_len(map));
> +             map->data = NULL;
> +     }
>       if (map->base != NULL) {
>               munmap(map->base, perf_mmap__mmap_len(map));
>               map->base = NULL;
> @@ -190,6 +194,14 @@ int perf_mmap__mmap(struct perf_mmap *map, struct 
> mmap_params *mp, int fd)
>               map->base = NULL;
>               return -1;
>       }
> +     map->data = mmap(NULL, perf_mmap__mmap_len(map), PROT_READ | PROT_WRITE,
> +                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

hum, why does map->data need to be mmap-ed?

jirka