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perf namespaces: Add helper nsinfo__is_in_root_namespace()

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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.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: John Garry <john.garry@huawei.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonatan Goldschmidt <yonatan.goldschmidt@granulate.io>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20211212134721.1721245-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Leo Yan 2021-12-12 21:47:20 +08:00 committed by Arnaldo Carvalho de Melo
parent 017f7d1fac
commit 5d28a17c1c
2 changed files with 48 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

76
tools/perf/util/namespaces.c
View File

@ -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;
}

2
tools/perf/util/namespaces.h
View File

@ -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) {