[PATCH] bug: Fix no-return-statement warning with !CONFIG_BUG

From: Adrian Hunter <adrian.hunter@intel.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
	"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Sven Schnelle <svens@linux.ibm.com>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Andy Lutomirski <luto@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	John Stultz <jstultz@google.com>, Stephen Boyd <sboyd@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Anna-Maria Behnsen <anna-maria@linutronix.de>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	linux-s390@vger.kernel.org
Subject: [PATCH] bug: Fix no-return-statement warning with !CONFIG_BUG
Date: Wed, 10 Apr 2024 18:32:12 +0300	[thread overview]
Message-ID: <20240410153212.127477-1-adrian.hunter@intel.com> (raw)

BUG() does not return, and arch implementations of BUG() use unreachable()
or other non-returning code. However with !CONFIG_BUG, the default
implementation is often used instead, and that does not do that. x86 always
uses its own implementation, but powerpc with !CONFIG_BUG gives a build
error:

  kernel/time/timekeeping.c: In function ‘timekeeping_debug_get_ns’:
  kernel/time/timekeeping.c:286:1: error: no return statement in function
  returning non-void [-Werror=return-type]

Add unreachable() to default !CONFIG_BUG BUG() implementation.

Fixes: e8e9d21a5df6 ("timekeeping: Refactor timekeeping helpers")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYvjdZCW=7ZGxS6A_3bysjQ56YF7S-+PNLQ_8a4DKh1Bhg@mail.gmail.com/
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 include/asm-generic/bug.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h
index 6e794420bd39..b7de3a4eade1 100644
--- a/include/asm-generic/bug.h
+++ b/include/asm-generic/bug.h
@@ -156,7 +156,10 @@ extern __printf(1, 2) void __warn_printk(const char *fmt, ...);
 
 #else /* !CONFIG_BUG */
 #ifndef HAVE_ARCH_BUG
-#define BUG() do {} while (1)
+#define BUG() do {		\
+	do {} while (1);	\
+	unreachable();		\
+} while (0)
 #endif
 
 #ifndef HAVE_ARCH_BUG_ON
-- 
2.34.1

