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authorJiri Olsa <jolsa@kernel.org>2018-11-01 18:00:01 +0100
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-11-19 12:12:26 -0800
commitb01c1f69c8660eaeab7d365cd570103c5c073a02 (patch)
treee1ab044702056dbba650751977fae990e60e4a0b /tools
parenttools build feature: Check if get_current_dir_name() is available (diff)
downloadlinux-dev-b01c1f69c8660eaeab7d365cd570103c5c073a02.tar.xz
linux-dev-b01c1f69c8660eaeab7d365cd570103c5c073a02.zip
perf tools: Restore proper cwd on return from mnt namespace
When reporting on 'record' server we try to retrieve/use the mnt namespace of the profiled tasks. We use following API with cookie to hold the return namespace, roughly: nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc) setns(newns, 0); ... new ns related open.. ... nsinfo__mountns_exit(struct nscookie *nc) setns(nc->oldns) Once finished we setns to old namespace, which also sets the current working directory (cwd) to "/", trashing the cwd we had. This is mostly fine, because we use absolute paths almost everywhere, but it screws up 'perf diff': # perf diff failed to open perf.data: No such file or directory (try 'perf record' first) ... Adding the current working directory to be part of the cookie and restoring it in the nsinfo__mountns_exit call. Signed-off-by: Jiri Olsa <jolsa@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Krister Johansen <kjlx@templeofstupid.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Fixes: 843ff37bb59e ("perf symbols: Find symbols in different mount namespace") Link: http://lkml.kernel.org/r/20181101170001.30019-1-jolsa@kernel.org [ No need to check for NULL args for free(), use zfree() for struct members ] Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/util/namespaces.c17
-rw-r--r--tools/perf/util/namespaces.h1
2 files changed, 16 insertions, 2 deletions
diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
index cf8bd123cf73..aed170bd4384 100644
--- a/tools/perf/util/namespaces.c
+++ b/tools/perf/util/namespaces.c
@@ -18,6 +18,7 @@
#include <stdio.h>
#include <string.h>
#include <unistd.h>
+#include <asm/bug.h>
struct namespaces *namespaces__new(struct namespaces_event *event)
{
@@ -186,6 +187,7 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
char curpath[PATH_MAX];
int oldns = -1;
int newns = -1;
+ char *oldcwd = NULL;
if (nc == NULL)
return;
@@ -199,9 +201,13 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
return;
+ oldcwd = get_current_dir_name();
+ if (!oldcwd)
+ return;
+
oldns = open(curpath, O_RDONLY);
if (oldns < 0)
- return;
+ goto errout;
newns = open(nsi->mntns_path, O_RDONLY);
if (newns < 0)
@@ -210,11 +216,13 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
if (setns(newns, CLONE_NEWNS) < 0)
goto errout;
+ nc->oldcwd = oldcwd;
nc->oldns = oldns;
nc->newns = newns;
return;
errout:
+ free(oldcwd);
if (oldns > -1)
close(oldns);
if (newns > -1)
@@ -223,11 +231,16 @@ errout:
void nsinfo__mountns_exit(struct nscookie *nc)
{
- if (nc == NULL || nc->oldns == -1 || nc->newns == -1)
+ if (nc == NULL || nc->oldns == -1 || nc->newns == -1 || !nc->oldcwd)
return;
setns(nc->oldns, CLONE_NEWNS);
+ if (nc->oldcwd) {
+ WARN_ON_ONCE(chdir(nc->oldcwd));
+ zfree(&nc->oldcwd);
+ }
+
if (nc->oldns > -1) {
close(nc->oldns);
nc->oldns = -1;
diff --git a/tools/perf/util/namespaces.h b/tools/perf/util/namespaces.h
index cae1a9a39722..d5f46c09ea31 100644
--- a/tools/perf/util/namespaces.h
+++ b/tools/perf/util/namespaces.h
@@ -38,6 +38,7 @@ struct nsinfo {
struct nscookie {
int oldns;
int newns;
+ char *oldcwd;
};
int nsinfo__init(struct nsinfo *nsi);