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Date: Wed, 7 Oct 2015 10:18:54 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Matt Mullins <mmullins@twopensource.com>
Cc: acme@kernel.org, Vinson Lee <vlee@twopensource.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Kan Liang <kan.liang@intel.com>, Andi Kleen <ak@linux.intel.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf tools: get version from uname(2), not /proc
Message-ID: <20151007081854.GA20302@krava.landal.opennet>
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On Tue, Oct 06, 2015 at 03:53:14PM -0700, Matt Mullins wrote:
> Tools in kmod (e.g. modprobe) compose the module path from the release
> from uname(2).  Because we use the UNAME26 personality, we need perf to
> find modules located at the same path as the system tools.

I guess it's easy to google this up, but could you
please state in the changelog what's the difference
between the current version and the UNAME26 one?

Also state (and check) this change wouldn't affect other
parts of the code that use this version (if there's any).

thanks,
jirka

> 
> Signed-off-by: Matt Mullins <mmullins@twopensource.com>
> Cc: Vinson Lee <vlee@twopensource.com>
> ---
>  tools/perf/util/machine.c | 28 ++++++----------------------
>  1 file changed, 6 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 5ef90be2a249..51199bc271e9 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -11,6 +11,7 @@
>  #include "vdso.h"
>  #include <stdbool.h>
>  #include <symbol/kallsyms.h>
> +#include <sys/utsname.h>
>  #include "unwind.h"
>  #include "linux/hash.h"
>  
> @@ -903,31 +904,14 @@ static void map_groups__fixup_end(struct map_groups *mg)
>  		__map_groups__fixup_end(mg, i);
>  }
>  
> -static char *get_kernel_version(const char *root_dir)
> +static char *get_kernel_version(void)
>  {
> -	char version[PATH_MAX];
> -	FILE *file;
> -	char *name, *tmp;
> -	const char *prefix = "Linux version ";
> +	struct utsname utsname;
>  
> -	sprintf(version, "%s/proc/version", root_dir);
> -	file = fopen(version, "r");
> -	if (!file)
> +	if (uname(&utsname))
>  		return NULL;
>  
> -	version[0] = '\0';
> -	tmp = fgets(version, sizeof(version), file);
> -	fclose(file);
> -
> -	name = strstr(version, prefix);
> -	if (!name)
> -		return NULL;
> -	name += strlen(prefix);
> -	tmp = strchr(name, ' ');
> -	if (tmp)
> -		*tmp = '\0';
> -
> -	return strdup(name);
> +	return strdup(utsname.release);
>  }
>  
>  static bool is_kmod_dso(struct dso *dso)
> @@ -1027,7 +1011,7 @@ static int machine__set_modules_path(struct machine *machine)
>  	char *version;
>  	char modules_path[PATH_MAX];
>  
> -	version = get_kernel_version(machine->root_dir);
> +	version = get_kernel_version();
>  	if (!version)
>  		return -1;
>  
> -- 
> 2.1.0
>