From 9cd65655585523adecd65b750e1537cdea84718e Mon Sep 17 00:00:00 2001
From: Alexey Dobriyan <adobriyan@gmail.com>
Date: Tue, 10 Apr 2018 16:31:45 -0700
Subject: [PATCH] proc: test /proc/self/wchan

This patch starts testing /proc.  Many more tests to come (I promise).

Read from /proc/self/wchan should always return "0" as current is in
TASK_RUNNING state while reading /proc/self/wchan.

Link: http://lkml.kernel.org/r/20180226212006.GA742@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 tools/testing/selftests/Makefile              |  1 +
 tools/testing/selftests/proc/.gitignore       |  1 +
 tools/testing/selftests/proc/Makefile         |  6 +++++
 tools/testing/selftests/proc/config           |  1 +
 .../testing/selftests/proc/proc-self-wchan.c  | 25 +++++++++++++++++++
 5 files changed, 34 insertions(+)
 create mode 100644 tools/testing/selftests/proc/.gitignore
 create mode 100644 tools/testing/selftests/proc/Makefile
 create mode 100644 tools/testing/selftests/proc/config
 create mode 100644 tools/testing/selftests/proc/proc-self-wchan.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 2fc410bc4f33..32aafa92074c 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -25,6 +25,7 @@ TARGETS += mqueue
 TARGETS += net
 TARGETS += nsfs
 TARGETS += powerpc
+TARGETS += proc
 TARGETS += pstore
 TARGETS += ptrace
 TARGETS += seccomp
diff --git a/tools/testing/selftests/proc/.gitignore b/tools/testing/selftests/proc/.gitignore
new file mode 100644
index 000000000000..4c851db80bd5
--- /dev/null
+++ b/tools/testing/selftests/proc/.gitignore
@@ -0,0 +1 @@
+/proc-self-wchan
diff --git a/tools/testing/selftests/proc/Makefile b/tools/testing/selftests/proc/Makefile
new file mode 100644
index 000000000000..592603a5d675
--- /dev/null
+++ b/tools/testing/selftests/proc/Makefile
@@ -0,0 +1,6 @@
+CFLAGS += -Wall -O2
+
+TEST_GEN_PROGS :=
+TEST_GEN_PROGS += proc-self-wchan
+
+include ../lib.mk
diff --git a/tools/testing/selftests/proc/config b/tools/testing/selftests/proc/config
new file mode 100644
index 000000000000..68fbd2b35884
--- /dev/null
+++ b/tools/testing/selftests/proc/config
@@ -0,0 +1 @@
+CONFIG_PROC_FS=y
diff --git a/tools/testing/selftests/proc/proc-self-wchan.c b/tools/testing/selftests/proc/proc-self-wchan.c
new file mode 100644
index 000000000000..b8d8728a6869
--- /dev/null
+++ b/tools/testing/selftests/proc/proc-self-wchan.c
@@ -0,0 +1,25 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <unistd.h>
+
+int main(void)
+{
+	char buf[64];
+	int fd;
+
+	fd = open("/proc/self/wchan", O_RDONLY);
+	if (fd == -1) {
+		if (errno == ENOENT)
+			return 2;
+		return 1;
+	}
+
+	buf[0] = '\0';
+	if (read(fd, buf, sizeof(buf)) != 1)
+		return 1;
+	if (buf[0] != '0')
+		return 1;
+	return 0;
+}