linux-kernel - [PATCH AUTOSEL 4.9 07/17] um: Give start_idle

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Date:   Tue, 13 Nov 2018 00:52:13 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     stable@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Richard Weinberger <richard@....at>,
        Sasha Levin <sashal@...nel.org>, linux-um@...ts.infradead.org
Subject: [PATCH AUTOSEL 4.9 07/17] um: Give start_idle_thread() a return code

From: Richard Weinberger <richard@....at>

[ Upstream commit 7ff1e34bbdc15acab823b1ee4240e94623d50ee8 ]

Fixes:
arch/um/os-Linux/skas/process.c:613:1: warning: control reaches end of
non-void function [-Wreturn-type]

longjmp() never returns but gcc still warns that the end of the function
can be reached.
Add a return code and debug aid to detect this impossible case.

Signed-off-by: Richard Weinberger <richard@....at>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/um/os-Linux/skas/process.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 23025d645160..0a99d4515065 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -578,6 +578,11 @@ int start_idle_thread(void *stack, jmp_buf *switch_buf)
 		fatal_sigsegv();
 	}
 	longjmp(*switch_buf, 1);
+
+	/* unreachable */
+	printk(UM_KERN_ERR "impossible long jump!");
+	fatal_sigsegv();
+	return 0;
 }
 
 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
-- 
2.17.1