Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     gwml@vger.gnuweeb.org, kernel-team@fb.com, w@lwt.eu,
        Willy Tarreau <w@1wt.eu>,
        "Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH nolibc 08/18] selftests/nolibc: exit with poweroff on success when getpid() == 1
Date:   Wed, 31 Aug 2022 11:21:38 -0700
Message-Id: <20220831182148.2698489-10-paulmck@kernel.org>
In-Reply-To: <20220831182113.GA2697286@paulmck-ThinkPad-P17-Gen-1>
References: <20220831182113.GA2697286@paulmck-ThinkPad-P17-Gen-1>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Willy Tarreau <w@1wt.eu>

The idea is to ease automated testing under qemu. If the test succeeds
while running as PID 1, indicating the system was booted with init=/test,
let's just power off so that qemu can exit with a successful code. In
other situations it will exit and provoke a panic, which may be caught
for example with CONFIG_PVPANIC.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index b928f099431f7..291d96bfd7c12 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -626,6 +626,20 @@ int main(int argc, char **argv, char **envp)
 	}
 
 	printf("Total number of errors: %d\n", ret);
+
+	if (getpid() == 1) {
+		/* we're running as init, there's no other process on the
+		 * system, thus likely started from a VM for a quick check.
+		 * Exiting will provoke a kernel panic that may be reported
+		 * as an error by Qemu or the hypervisor, while stopping
+		 * cleanly will often be reported as a success. This allows
+		 * to use the output of this program for bisecting kernels.
+		 */
+		printf("Leaving init with final status: %d\n", !!ret);
+		if (ret == 0)
+			reboot(LINUX_REBOOT_CMD_POWER_OFF);
+	}
+
 	printf("Exiting with status %d\n", !!ret);
 	return !!ret;
 }
-- 
2.31.1.189.g2e36527f23