Em Mon, Sep 09, 2013 at 09:21:55PM +0800, Chenggang Qin escreveu:
> From: Chenggang Qin <chenggang....@taobao.com>
> 
> Vdso is only one in a system. It is not necessory to traverse the
> macine->user_dsos list when looking for the dso of vdso.
> The flag vdso_found should be replaced by a pointor that point to the dso of
> vdso. If the pointer is NULL, dso of vdso have not been created. Else, the
> pointor can be returned directly in function vdso__dso_findnew().
> The list traversing can be avoided by this method.
> Thanks.
> 
> Cc: David Ahern <dsah...@gmail.com>
> Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
> Cc: Paul Mackerras <pau...@samba.org>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Arnaldo Carvalho de Melo <a...@ghostprotocols.net>
> Cc: Arjan van de Ven <ar...@linux.intel.com>
> Cc: Namhyung Kim <namhy...@gmail.com>
> Cc: Yanmin Zhang <yanmin.zh...@intel.com>
> Cc: Wu Fengguang <fengguang...@intel.com>
> Cc: Mike Galbraith <efa...@gmx.de>
> Cc: Andrew Morton <a...@linux-foundation.org>
> Signed-off-by: Chenggang Qin <chenggang....@taobao.com>
> 
> ---
>  tools/perf/util/vdso.c |   22 ++++++++--------------
>  1 files changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
> index 3915982..8022ef0 100644
> --- a/tools/perf/util/vdso.c
> +++ b/tools/perf/util/vdso.c
> @@ -13,7 +13,7 @@
>  #include "symbol.h"
>  #include "linux/string.h"
>  
> -static bool vdso_found;
> +static struct dso *vdso_dso = NULL;
>  static char vdso_file[] = "/tmp/perf-vdso.so-XXXXXX";
>  
>  static int find_vdso_map(void **start, void **end)
> @@ -55,9 +55,6 @@ static char *get_file(void)
>       size_t size;
>       int fd;
>  
> -     if (vdso_found)
> -             return vdso_file;
> -
>       if (find_vdso_map(&start, &end))
>               return NULL;
>  
> @@ -79,33 +76,30 @@ static char *get_file(void)
>   out:
>       free(buf);
>  
> -     vdso_found = (vdso != NULL);
>       return vdso;
>  }
>  
>  void vdso__exit(void)
>  {
> -     if (vdso_found)
> +     if (vdso_dso)
>               unlink(vdso_file);

Don't we have to delete the vfso_dso and set it to NULL?

>  }
>  
>  struct dso *vdso__dso_findnew(struct list_head *head)
>  {
> -     struct dso *dso = dsos__find(head, VDSO__MAP_NAME, true);
> -
> -     if (!dso) {
> +     if (!vdso_dso) {
>               char *file;
>  
>               file = get_file();
>               if (!file)
>                       return NULL;
>  
> -             dso = dso__new(VDSO__MAP_NAME);
> -             if (dso != NULL) {
> -                     dsos__add(head, dso);
> -                     dso__set_long_name(dso, file);
> +             vdso_dso = dso__new(VDSO__MAP_NAME);
> +             if (vdso_dso != NULL) {
> +                     dsos__add(head, vdso_dso);
> +                     dso__set_long_name(vdso_dso, file);
>               }
>       }
>  
> -     return dso;
> +     return vdso_dso;
>  }
> -- 
> 1.7.8.rc2.5.g815b
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