linux-kernel - Re: [PATCH] perf machine: Search for modules in %s/lib/modules/%s

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Date:	Sun, 27 Apr 2014 12:05:56 +0200
From:	Jiri Olsa <jolsa@...hat.com>
To:	Richard Yao <ryao@...too.org>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Adrian Hunter <adrian.hunter@...el.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf machine: Search for modules in %s/lib/modules/%s

On Sat, Apr 26, 2014 at 01:17:55PM -0400, Richard Yao wrote:
> Modules installed outside of the kernel's build system should go into
> "%s/lib/modules/%s/extra", but at present, perf will only look at them
> when they are in "%s/lib/modules/%s/kernel". Lets encourage good
> citizenship by relaxing this requirement to "%s/lib/modules/%s". This
> way open source modules that are out-of-tree have no incentive to start
> populating a directory reserved for in-kernel modules and I can stop
> hex-editing my system's perf binary when profiling OSS out-of-tree
> modules.
> 
> Feedback from Namhyung Kim correctly revealed that the hex-edits that I
> had been doing meant that perf was also traversing the build and source
> symlinks in %s/lib/modules/%s. That is undesireable, so we explicitly
> exclude them from traversal with a minor tweak to the traversal routine.

looks good to me, Namhyung?

thanks,
jirka

> 
> Signed-off-by: Richard Yao <ryao@...too.org>
> ---
>  tools/perf/util/machine.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index a53cd0b..27c2a5e 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -717,7 +717,7 @@ static char *get_kernel_version(const char *root_dir)
>  }
>  
>  static int map_groups__set_modules_path_dir(struct map_groups *mg,
> -				const char *dir_name)
> +				const char *dir_name, int depth)
>  {
>  	struct dirent *dent;
>  	DIR *dir = opendir(dir_name);
> @@ -742,7 +742,15 @@ static int map_groups__set_modules_path_dir(struct map_groups *mg,
>  			    !strcmp(dent->d_name, ".."))
>  				continue;
>  
> -			ret = map_groups__set_modules_path_dir(mg, path);
> +			/* Do not follow top-level source and build symlinks */
> +			if (depth == 0) {
> +				if (!strcmp(dent->d_name, "source") ||
> +				    !strcmp(dent->d_name, "build"))
> +					continue;
> +			}
> +
> +			ret = map_groups__set_modules_path_dir(mg, path,
> +							       depth + 1);
>  			if (ret < 0)
>  				goto out;
>  		} else {
> @@ -786,11 +794,11 @@ static int machine__set_modules_path(struct machine *machine)
>  	if (!version)
>  		return -1;
>  
> -	snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s/kernel",
> +	snprintf(modules_path, sizeof(modules_path), "%s/lib/modules/%s",
>  		 machine->root_dir, version);
>  	free(version);
>  
> -	return map_groups__set_modules_path_dir(&machine->kmaps, modules_path);
> +	return map_groups__set_modules_path_dir(&machine->kmaps, modules_path, 0);
>  }
>  
>  static int machine__create_module(void *arg, const char *name, u64 start)
> -- 
> 1.8.3.2
> 
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