linux-kernel - Re: [PATCH perf/core v5 02/15] perf-buildid-cache: Use path/to/bin/buildid/elf instead of path/to/bin/buildid

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Message-ID: <20160427212350.GR11033@kernel.org>
Date:	Wed, 27 Apr 2016 18:23:50 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Masami Hiramatsu <mhiramat@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Hemant Kumar <hemant@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>
Subject: Re: [PATCH perf/core v5 02/15] perf-buildid-cache: Use
 path/to/bin/buildid/elf instead of path/to/bin/buildid

Em Thu, Apr 28, 2016 at 03:37:23AM +0900, Masami Hiramatsu escreveu:
> From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> 
> Use path/to/bin/buildid/elf instead of path/to/bin/buildid
> to store corresponding elf binary.
> This also stores vdso in buildid/vdso, kallsyms in buildid/kallsyms.
> 
> Note that the existing caches are not updated until user adds
> or updates the cache. Anyway, if there is the old style build-id
> cache it falls back to use it. (IOW, it is backward compatible)
> 
> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> ---
>  Changes in v5:
>   - Support old style buildid caches.

> +	/* Remove old style build-id cache */
> +	if (__is_regular_file(dir_name))
> +		if (unlink(dir_name))
> +			goto out_free;

Shouldn't this just fail and require the user to use --force/-f or purge
first?

- Arnaldo

>  	if (mkdir_p(dir_name, 0755))
>  		goto out_free;
>  
> -	if (asprintf(&filename, "%s/%s", dir_name, sbuild_id) < 0) {
> +	/* Save the allocated buildid dirname */
> +	if (asprintf(&filename, "%s/%s", dir_name,
> +		     build_id_cache__basename(is_kallsyms, is_vdso)) < 0) {
>  		filename = NULL;
>  		goto out_free;
>  	}
> @@ -437,7 +479,7 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>  			goto out_free;
>  	}
>  
> -	if (!build_id__filename(sbuild_id, linkname, size))
> +	if (!build_id_cache__linkname(sbuild_id, linkname, size))
>  		goto out_free;
>  	tmp = strrchr(linkname, '/');
>  	*tmp = '\0';
> @@ -446,10 +488,10 @@ int build_id_cache__add_s(const char *sbuild_id, const char *name,
>  		goto out_free;
>  
>  	*tmp = '/';
> -	targetname = filename + strlen(buildid_dir) - 5;
> -	memcpy(targetname, "../..", 5);
> +	tmp = dir_name + strlen(buildid_dir) - 5;
> +	memcpy(tmp, "../..", 5);
>  
> -	if (symlink(targetname, linkname) == 0)
> +	if (symlink(tmp, linkname) == 0)
>  		err = 0;
>  out_free:
>  	if (!is_kallsyms)
> @@ -474,7 +516,7 @@ static int build_id_cache__add_b(const u8 *build_id, size_t build_id_size,
>  bool build_id_cache__cached(const char *sbuild_id)
>  {
>  	bool ret = false;
> -	char *filename = build_id__filename(sbuild_id, NULL, 0);
> +	char *filename = build_id_cache__linkname(sbuild_id, NULL, 0);
>  
>  	if (filename && !access(filename, F_OK))
>  		ret = true;
> @@ -493,7 +535,7 @@ int build_id_cache__remove_s(const char *sbuild_id)
>  	if (filename == NULL || linkname == NULL)
>  		goto out_free;
>  
> -	if (!build_id__filename(sbuild_id, linkname, size))
> +	if (!build_id_cache__linkname(sbuild_id, linkname, size))
>  		goto out_free;
>  
>  	if (access(linkname, F_OK))
> @@ -511,7 +553,7 @@ int build_id_cache__remove_s(const char *sbuild_id)
>  	tmp = strrchr(linkname, '/') + 1;
>  	snprintf(tmp, size - (tmp - linkname), "%s", filename);
>  
> -	if (unlink(linkname))
> +	if (rm_rf(linkname))
>  		goto out_free;
>  
>  	err = 0;
> @@ -523,7 +565,7 @@ out_free:
>  
>  static int dso__cache_build_id(struct dso *dso, struct machine *machine)
>  {
> -	bool is_kallsyms = dso->kernel && dso->long_name[0] != '/';
> +	bool is_kallsyms = dso__is_kallsyms(dso);
>  	bool is_vdso = dso__is_vdso(dso);
>  	const char *name = dso->long_name;
>  	char nm[PATH_MAX];
> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
> index 0953280..76d79d0 100644
> --- a/tools/perf/util/dso.h
> +++ b/tools/perf/util/dso.h
> @@ -349,6 +349,11 @@ static inline bool dso__is_kcore(struct dso *dso)
>  	       dso->binary_type == DSO_BINARY_TYPE__GUEST_KCORE;
>  }
>  
> +static inline bool dso__is_kallsyms(struct dso *dso)
> +{
> +	return dso->kernel && dso->long_name[0] != '/';
> +}
> +
>  void dso__free_a2l(struct dso *dso);
>  
>  enum dso_type dso__type(struct dso *dso, struct machine *machine);
> diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
> index 415c4f6..9463c7d 100644
> --- a/tools/perf/util/symbol.c
> +++ b/tools/perf/util/symbol.c
> @@ -1685,13 +1685,18 @@ static char *dso__find_kallsyms(struct dso *dso, struct map *map)
>  	if (!find_matching_kcore(map, path, sizeof(path)))
>  		return strdup(path);
>  
> -	scnprintf(path, sizeof(path), "%s/[kernel.kallsyms]/%s",
> +	scnprintf(path, sizeof(path), "%s/[kernel.kallsyms]/%s/kallsyms",
>  		  buildid_dir, sbuild_id);
> -
> +	/* Try old style kallsyms cache */
>  	if (access(path, F_OK)) {
> -		pr_err("No kallsyms or vmlinux with build-id %s was found\n",
> -		       sbuild_id);
> -		return NULL;
> +		scnprintf(path, sizeof(path), "%s/[kernel.kallsyms]/%s",
> +			  buildid_dir, sbuild_id);
> +
> +		if (access(path, F_OK)) {
> +			pr_err("No kallsyms or vmlinux with build-id %s was found\n",
> +			       sbuild_id);
> +			return NULL;
> +		}
>  	}
>  
>  	return strdup(path);