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| author | Jiri Olsa <jolsa@kernel.org> | 2018-11-01 18:00:01 +0100 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-11-19 12:12:26 -0800 |
| commit | b01c1f69c8660eaeab7d365cd570103c5c073a02 (patch) | |
| tree | e1ab044702056dbba650751977fae990e60e4a0b /tools/perf | |
| parent | 8feb8efef97a134933620071e0b6384cb3238b4e (diff) | |
| download | linux-b01c1f69c8660eaeab7d365cd570103c5c073a02.tar.bz2 | |
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/perf')
| -rw-r--r-- | tools/perf/util/namespaces.c | 17 | ||||
| -rw-r--r-- | tools/perf/util/namespaces.h | 1 |
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); |