tools build: Add test for setns()

And provide an alternative implementation to keep perf building on older
distros as we're about to add initial support for namespaces.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Krister Johansen <kjlx@templeofstupid.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bqdwijunhjlvps1ardykhw1i@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 21 insertions, 0 deletions

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index bdf0e87f9b29..37d203c4cd1f 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -330,6 +330,11 @@ ifeq ($(feature-sched_getcpu), 1)
   CFLAGS += -DHAVE_SCHED_GETCPU_SUPPORT
 endif
 
+ifeq ($(feature-setns), 1)
+  CFLAGS += -DHAVE_SETNS_SUPPORT
+  $(call detected,CONFIG_SETNS)
+endif
+
 ifndef NO_LIBELF
   CFLAGS += -DHAVE_LIBELF_SUPPORT
   EXTLIBS += -lelf
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index 79dea95a7f68..7580fe4d5d30 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -104,6 +104,10 @@ ifndef CONFIG_LIBELF
 libperf-y += symbol-minimal.o
 endif
 
+ifndef CONFIG_SETNS
+libperf-y += setns.o
+endif
+
 libperf-$(CONFIG_DWARF) += probe-finder.o
 libperf-$(CONFIG_DWARF) += dwarf-aux.o
 libperf-$(CONFIG_DWARF) += dwarf-regs.o
diff --git a/tools/perf/util/setns.c b/tools/perf/util/setns.c
new file mode 100644
index 000000000000..ce8fc290fce8
--- /dev/null
+++ b/tools/perf/util/setns.c
@@ -0,0 +1,8 @@
+#include "util.h"
+#include <unistd.h>
+#include <sys/syscall.h>
+
+int setns(int fd, int nstype)
+{
+        return syscall(__NR_setns, fd, nstype);
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 2c9e58a45310..1e5fe1d9ec32 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -58,4 +58,8 @@ const char *perf_tip(const char *dirpath);
 int sched_getcpu(void);
 #endif
 
+#ifndef HAVE_SETNS_SUPPORT
+int setns(int fd, int nstype);
+#endif
+
 #endif /* GIT_COMPAT_UTIL_H */