Re: [RFC/PATCH 04/38] perf tools: pass perf_mmap desc directly

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Oct 02, 2015 at 02:18:45PM +0900, Namhyung Kim escreveu:
> Pass struct perf_mmap to mmap handling functions directly.  This will
> be used by both of normal mmap and track mmap later.
> 
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
> ---
>  tools/perf/util/evlist.c | 24 +++++++++++++++---------
>  tools/perf/util/evlist.h |  1 +
>  2 files changed, 16 insertions(+), 9 deletions(-)
> 
> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
> index 042dffc67986..8d31883cbeb8 100644
> --- a/tools/perf/util/evlist.c
> +++ b/tools/perf/util/evlist.c
> @@ -921,8 +921,8 @@ struct mmap_params {
>  	struct auxtrace_mmap_params auxtrace_mp;
>  };
>  
> -static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
> -			       struct mmap_params *mp, int fd)
> +static int perf_mmap__mmap(struct perf_mmap *desc,
> +			   struct mmap_params *mp, int fd)
>  {
>  	/*
>  	 * The last one will be done at perf_evlist__mmap_consume(), so that we
> @@ -937,21 +937,26 @@ static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
>  	 * evlist layer can't just drop it when filtering events in
>  	 * perf_evlist__filter_pollfd().
>  	 */
> -	atomic_set(&evlist->mmap[idx].refcnt, 2);
> -	evlist->mmap[idx].prev = 0;
> -	evlist->mmap[idx].mask = perf_evlist__mmap_mask(mp->len);
> -	evlist->mmap[idx].base = mmap(NULL, mp->len, mp->prot,
> +	atomic_set(&desc->refcnt, 2);
> +	desc->prev = 0;
> +	desc->mask = perf_evlist__mmap_mask(mp->len);
> +	desc->base = mmap(NULL, mp->len, mp->prot,
>  				      MAP_SHARED, fd, 0);
> -	if (evlist->mmap[idx].base == MAP_FAILED) {
> +	if (desc->base == MAP_FAILED) {
>  		pr_debug2("failed to mmap perf event ring buffer, error %d\n",
>  			  errno);
> -		evlist->mmap[idx].base = NULL;
> +		desc->base = NULL;
>  		return -1;
>  	}
>  
>  	return 0;
>  }
>  
> +struct perf_mmap *perf_evlist__mmap_desc(struct perf_evlist *evlist, int idx)
> +{
> +	return &evlist->mmap[idx];
> +}
> +

What does 'desc' stands for? Why not just use evlist->mmap[idx]?

>  static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>  				       struct mmap_params *mp, int cpu,
>  				       int thread, int *output)
> @@ -960,6 +965,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>  
>  	evlist__for_each(evlist, evsel) {
>  		int fd;
> +		struct perf_mmap *desc = perf_evlist__mmap_desc(evlist, idx);
>  
>  		if (evsel->system_wide && thread)
>  			continue;
> @@ -968,7 +974,7 @@ static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
>  
>  		if (*output == -1) {
>  			*output = fd;
> -			if (__perf_evlist__mmap(evlist, idx, mp, *output) < 0)
> +			if (perf_mmap__mmap(desc, mp, *output) < 0)
>  				return -1;
>  
>  			if (auxtrace_mmap__mmap(&evlist->auxtrace_mmap[idx],
> diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
> index 51574ce8ac69..79f8245300ad 100644
> --- a/tools/perf/util/evlist.h
> +++ b/tools/perf/util/evlist.h
> @@ -145,6 +145,7 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
>  int perf_evlist__mmap(struct perf_evlist *evlist, unsigned int pages,
>  		      bool overwrite);
>  void perf_evlist__munmap(struct perf_evlist *evlist);
> +struct perf_mmap *perf_evlist__mmap_desc(struct perf_evlist *evlist, int idx);
>  
>  void perf_evlist__disable(struct perf_evlist *evlist);
>  void perf_evlist__enable(struct perf_evlist *evlist);
> -- 
> 2.6.0