linux-kernel - Re: [PATCH v1 1/2] perf namespaces: Add helper nsinfo__is_in_root

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Date:   Mon, 13 Dec 2021 15:20:30 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Leo Yan <leo.yan@...aro.org>
Cc:     Jiri Olsa <jolsa@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Jin Yao <yao.jin@...ux.intel.com>,
        John Garry <john.garry@...wei.com>,
        Yonatan Goldschmidt <yonatan.goldschmidt@...nulate.io>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v1 1/2] perf namespaces: Add helper
 nsinfo__is_in_root_namespace()

Em Sun, Dec 12, 2021 at 09:47:20PM +0800, Leo Yan escreveu:
> Refactors code for gathering PID infos, it creates the function
> nsinfo__get_nspid() to parse process 'status' node in folder '/proc'.
> 
> Base on the refactoring, this patch introduces a new helper
> nsinfo__is_in_root_namespace(), it returns true when the caller runs in
> the root PID namespace.

Thanks, applied.

- Arnaldo

 
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
>  tools/perf/util/namespaces.c | 76 ++++++++++++++++++++++--------------
>  tools/perf/util/namespaces.h |  2 +
>  2 files changed, 48 insertions(+), 30 deletions(-)
> 
> diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
> index 608b20c72a5c..48aa3217300b 100644
> --- a/tools/perf/util/namespaces.c
> +++ b/tools/perf/util/namespaces.c
> @@ -60,17 +60,49 @@ void namespaces__free(struct namespaces *namespaces)
>  	free(namespaces);
>  }
>  
> +static int nsinfo__get_nspid(struct nsinfo *nsi, const char *path)
> +{
> +	FILE *f = NULL;
> +	char *statln = NULL;
> +	size_t linesz = 0;
> +	char *nspid;
> +
> +	f = fopen(path, "r");
> +	if (f == NULL)
> +		return -1;
> +
> +	while (getline(&statln, &linesz, f) != -1) {
> +		/* Use tgid if CONFIG_PID_NS is not defined. */
> +		if (strstr(statln, "Tgid:") != NULL) {
> +			nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'),
> +						     NULL, 10);
> +			nsi->nstgid = nsi->tgid;
> +		}
> +
> +		if (strstr(statln, "NStgid:") != NULL) {
> +			nspid = strrchr(statln, '\t');
> +			nsi->nstgid = (pid_t)strtol(nspid, NULL, 10);
> +			/*
> +			 * If innermost tgid is not the first, process is in a different
> +			 * PID namespace.
> +			 */
> +			nsi->in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
> +			break;
> +		}
> +	}
> +
> +	fclose(f);
> +	free(statln);
> +	return 0;
> +}
> +
>  int nsinfo__init(struct nsinfo *nsi)
>  {
>  	char oldns[PATH_MAX];
>  	char spath[PATH_MAX];
>  	char *newns = NULL;
> -	char *statln = NULL;
> -	char *nspid;
>  	struct stat old_stat;
>  	struct stat new_stat;
> -	FILE *f = NULL;
> -	size_t linesz = 0;
>  	int rv = -1;
>  
>  	if (snprintf(oldns, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
> @@ -100,34 +132,9 @@ int nsinfo__init(struct nsinfo *nsi)
>  	if (snprintf(spath, PATH_MAX, "/proc/%d/status", nsi->pid) >= PATH_MAX)
>  		goto out;
>  
> -	f = fopen(spath, "r");
> -	if (f == NULL)
> -		goto out;
> -
> -	while (getline(&statln, &linesz, f) != -1) {
> -		/* Use tgid if CONFIG_PID_NS is not defined. */
> -		if (strstr(statln, "Tgid:") != NULL) {
> -			nsi->tgid = (pid_t)strtol(strrchr(statln, '\t'),
> -						     NULL, 10);
> -			nsi->nstgid = nsi->tgid;
> -		}
> -
> -		if (strstr(statln, "NStgid:") != NULL) {
> -			nspid = strrchr(statln, '\t');
> -			nsi->nstgid = (pid_t)strtol(nspid, NULL, 10);
> -			/* If innermost tgid is not the first, process is in a different
> -			 * PID namespace.
> -			 */
> -			nsi->in_pidns = (statln + sizeof("NStgid:") - 1) != nspid;
> -			break;
> -		}
> -	}
> -	rv = 0;
> +	rv = nsinfo__get_nspid(nsi, spath);
>  
>  out:
> -	if (f != NULL)
> -		(void) fclose(f);
> -	free(statln);
>  	free(newns);
>  	return rv;
>  }
> @@ -299,3 +306,12 @@ int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi)
>  
>  	return ret;
>  }
> +
> +bool nsinfo__is_in_root_namespace(void)
> +{
> +	struct nsinfo nsi;
> +
> +	memset(&nsi, 0x0, sizeof(nsi));
> +	nsinfo__get_nspid(&nsi, "/proc/self/status");
> +	return !nsi.in_pidns;
> +}
> diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
> index ad9775db7b9c..9ceea9643507 100644
> --- a/tools/perf/util/namespaces.h
> +++ b/tools/perf/util/namespaces.h
> @@ -59,6 +59,8 @@ void nsinfo__mountns_exit(struct nscookie *nc);
>  char *nsinfo__realpath(const char *path, struct nsinfo *nsi);
>  int nsinfo__stat(const char *filename, struct stat *st, struct nsinfo *nsi);
>  
> +bool nsinfo__is_in_root_namespace(void);
> +
>  static inline void __nsinfo__zput(struct nsinfo **nsip)
>  {
>  	if (nsip) {
> -- 
> 2.25.1

-- 

- Arnaldo