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From:   Zhangjin Wu <falcon@tinylab.org>
To:     w@1wt.eu
Cc:     thomas@t-8ch.de, arnd@arndb.de, falcon@tinylab.org,
        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: [PATCH v1 08/17] selftests/nolibc: fix up failures when there is no procfs
Date:   Wed, 21 Jun 2023 21:03:07 +0800
Message-Id: <6ba1291bf6a687dbd0d7dd20c65583a535157b17.1687344643.git.falcon@tinylab.org>
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When there is no procfs support, the /proc is not mountable, but the
/proc directory has been created in the prepare() stage and therefore,
the checking of /proc in the run_syscall() stage will be always true and
at last will fail all of the procfs dependent test cases.

To solve this issue, one method is checking /proc/self instead of /proc,
another one is removing the /proc directory completely (when there is
really no procfs support), we apply the second method to avoid mislead
the users.

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 9673c338d42e..e5a218ef8a2d 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -928,8 +928,11 @@ int prepare(void)
 
 	/* try to mount /proc if not mounted. Silently fail otherwise */
 	if (stat("/proc/.", &stat_buf) == 0 || mkdir("/proc", 0755) == 0) {
-		if (stat("/proc/self", &stat_buf) != 0)
-			mount("/proc", "/proc", "proc", 0, 0);
+		if (stat("/proc/self", &stat_buf) != 0) {
+			/* If not mountable, remove /proc completely to avoid misuse */
+			if (mount("none", "/proc", "proc", 0, 0) != 0)
+				rmdir("/proc");
+		}
 	}
 
 	return 0;
-- 
2.25.1