From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.mainlining.org (mail.mainlining.org [5.75.144.95]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B99EA3793B8; Mon, 5 Oct 2026 12:06:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=5.75.144.95 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791201983; cv=none; b=EaK/zMdaEFQUnurFWOQTKNR610IbiTREkoBlOluXzn/dgunpIsqLQQBZXinlnrbochrLbWvFfuMTE0jiwc0J0qPGWtrxHfD/EFy5QzWyU7a2YvNHo7X0fZDrDgkD771qwQB2O3f6LURJLBDb50tOlNd9ElHJj7f6wPUIZHDqknI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791201983; c=relaxed/simple; bh=i0KnUM5v5QJil826Tj60TG6RtCKz0NN6pVnBO8O6ys0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OLKg2EV47QkrfKK40h4So6Sz8epPjMuKk9DdT9+cR0fwDJaKsTESvWcOXsXyTodrRjx8p1fbTihnYtgv/lOTUV0EKoDXywwAWBQDc6XC4zeJ/iicR+1jhvCuj2+/hxFDwHL3enK9i2i5bW9xflt9TZU5LqecQ5VhYgmsaRmiyYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mainlining.org; spf=pass smtp.mailfrom=mainlining.org; dkim=pass (2048-bit key) header.d=mainlining.org header.i=@mainlining.org header.b=c6X/5p4p; dkim=permerror (0-bit key) header.d=mainlining.org header.i=@mainlining.org header.b=3lAMB5Im; arc=none smtp.client-ip=5.75.144.95 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mainlining.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mainlining.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mainlining.org header.i=@mainlining.org header.b="c6X/5p4p"; dkim=permerror (0-bit key) header.d=mainlining.org header.i=@mainlining.org header.b="3lAMB5Im" DKIM-Signature: v=1; a=rsa-sha256; s=202507r; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1791201964; bh=gQiGga2Z4THQxcURrzEPZFq KmnssVIT4dSdk9XOrkDQ=; b=c6X/5p4pcLqfTbYSOffQRTPj+yYzQ6Ar88g9TgYQZB6jVLFSPB Re/YsXzw5lMY+JuIiJ4qULks/AMP7ZTQL1+31EQ2x+cHhhgZyA/DkJyP9xtU+Xm7Ll6rZ5GCuex JStQRds7rzzZu0kxPJq4/l42l8Bplmh0HO+nAwJ1v42VKuqDSf9Fy62pDStY9pEPWClynoJNqZ4 NvbUujIRW9W8mYXXfxcJnhAd7ogOPU12uBkLyi8nCjrHSJjzeao0F0WULN8HfK8ojke7WFGbF/b FZ3KiFDXv0OA+rIqfkD9X8iWSV0Xsvi8ilWQm3YrMbKfyfKbgJYGN8pYRFLMKjTRXxg==; DKIM-Signature: v=1; a=ed25519-sha256; s=202507e; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1791201964; bh=gQiGga2Z4THQxcURrzEPZFq KmnssVIT4dSdk9XOrkDQ=; b=3lAMB5Imfg+jAz+v8/50fhFT1WYag9oorC2vpN0PebrW6zQJ1Z rk/V4FA+NFPEcL/zeD+EZaca5OD3DR6UKuDw==; From: Bradley Morgan To: akpm@linux-foundation.org, vgupta@kernel.org, guoren@kernel.org, chris@zankel.net, jcmvbkbc@gmail.com Cc: arnd@arndb.de, paulmck@kernel.org, david.laight.linux@gmail.com, glaubitz@physik.fu-berlin.de, ysato@users.sourceforge.jp, dalias@libc.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org, brads@mainlining.org Subject: [PATCH v5 3/3] xtensa: Emulate two-byte cmpxchg Date: Mon, 5 Oct 2026 12:05:56 +0000 Message-ID: <20261005120556.383004-4-brads@mainlining.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261005120556.383004-1-brads@mainlining.org> References: <20261005120556.383004-1-brads@mainlining.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Xtensa has no two-byte atomic compare and swap, so the __cmpxchg() switch lets case 2 fall through to __cmpxchg_called_with_bad_pointer(), which is declared but never defined, so a two-byte cmpxchg() fails at link time. Route case 2 through the new cmpxchg_emu_u16(), which takes the old and new values as unsigned long and narrows them itself, so the call needs no extra casts. Signed-off-by: Bradley Morgan --- arch/xtensa/include/asm/cmpxchg.h | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h index b6db4838b175..8dea8e357fc0 100644 --- a/arch/xtensa/include/asm/cmpxchg.h +++ b/arch/xtensa/include/asm/cmpxchg.h @@ -76,6 +76,7 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size) { switch (size) { case 1: return cmpxchg_emu_u8(ptr, old, new); + case 2: return cmpxchg_emu_u16(ptr, old, new); case 4: return __cmpxchg_u32(ptr, old, new); default: __cmpxchg_called_with_bad_pointer(); return old; -- 2.53.0