Received-SPF: pass (google.com: domain of linux-kernel+bounces-181147-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Nathan Chancellor <nathan@kernel.org>
Date: Thu, 16 May 2024 07:03:41 -0700
Subject: [PATCH] x86/boot: Address clang -Wimplicit-fallthrough in
 vsprintf()
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
Message-Id: <20240516-x86-boot-fix-clang-implicit-fallthrough-v1-1-04dc320ca07c@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, 
 Borislav Petkov <bp@alien8.de>, Dave Hansen <dave.hansen@linux.intel.com>, 
 x86@kernel.org
Cc: Bill Wendling <morbo@google.com>, Justin Stitt <justinstitt@google.com>, 
 linux-kernel@vger.kernel.org, llvm@lists.linux.dev, patches@lists.linux.dev, 
 kernel test robot <lkp@intel.com>, Nathan Chancellor <nathan@kernel.org>

After enabling -Wimplicit-fallthrough for the x86 boot code, clang
warns:

  arch/x86/boot/printf.c:257:3: warning: unannotated fall-through between switch labels [-Wimplicit-fallthrough]
    257 |                 case 'u':
        |                 ^

Clang is a little more pedantic than GCC, which does not warn when
falling through to a case that is just break or return. Clang's version
is more in line with the kernel's own stance in deprecated.rst, which
states that all switch/case blocks must end in either break,
fallthrough, continue, goto, or return. Add the missing break to silence
the warning.

Fixes: dd0716c2b877 ("x86/boot: Add a fallthrough annotation")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202405162054.ryP73vy1-lkp@intel.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 arch/x86/boot/printf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/boot/printf.c b/arch/x86/boot/printf.c
index c0ec1dc355ab..51dc14b714f6 100644
--- a/arch/x86/boot/printf.c
+++ b/arch/x86/boot/printf.c
@@ -254,6 +254,8 @@ int vsprintf(char *buf, const char *fmt, va_list args)
 		case 'd':
 		case 'i':
 			flags |= SIGN;
+			break;
+
 		case 'u':
 			break;
 

---
base-commit: dd0716c2b87792ebea30864e7ad1df461d4c1525
change-id: 20240516-x86-boot-fix-clang-implicit-fallthrough-fc5c9bb19765

Best regards,
-- 
Nathan Chancellor <nathan@kernel.org>