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 684EC3EF65B; Wed, 16 Sep 2026 20:04:45 +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=1789589109; cv=none; b=r6DGTImJEFBy+QOCiM0lAYCSU6CbIyN0c3dQnUyiEjPwEEAGcp19SXLmh1srpGklqTTWj/UO7jscIa9CgGn504mwEmXuezUeU4Qqtb5EIVposswgdr0wzjxTKyjLnB5V0hZ7RWotsqfc0u8g5mOeBi3AC64Bb9+aamg3+HdNYZ0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789589109; c=relaxed/simple; bh=1ff5/nczEYO3kkyeg21AsMw/jo427+wb5UJ/kpXO3vM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kZ9m4dC93cp3g/gYH5ZdZZou6qaWKfaLDSCtOAPmqR2+dtGPfuxlPRnjhCt7gQe9dzJCEMrfLkEtifC5Uea87KIQKYrz/P6SUtemK+xdFbs/Q73vKYM9Qi6hcYF8pkXCdbZvrcTGsUQs49yxfnmoSRsUXKlSWfM3jP5f47/U0+U= 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=dHD1HWO+; dkim=permerror (0-bit key) header.d=mainlining.org header.i=@mainlining.org header.b=uI3PUxmR; 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="dHD1HWO+"; dkim=permerror (0-bit key) header.d=mainlining.org header.i=@mainlining.org header.b="uI3PUxmR" DKIM-Signature: v=1; a=rsa-sha256; s=202507r; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1789588935; bh=1OXxOnbJI64tKjJBlcCcfNg /vmHmtRmMcXj4ssSqyI8=; b=dHD1HWO+3ETnfnxub467tSSinQ6AbN2y51X23r7Bht5gWglVMM Nlok2iptk4U04M82fZ8leUzk+ihL0NaLL0vHYPP724yQVZpGa0nhB+gU/iFlpfsKkxixDusu7lr jNrcKoYFAtqETzQbBh+8faNx0fAIDAJzXgmjmFL/7O9pwJcm2qkOczsS+Y1C2rAGPhsY749WDAS 7QD6arsF02kSpsoXWAicZSTfVh/szo1ff2QIaozy+ivpS0WkK+HyoA64/bjnUA+WbHr4pf5zlmV ZEWf44Kg6LsJGRcm1aQhpiX9vRdMJUTsYyIhtKwB1iy5zZnB74NPLci+wPUR09zctmA==; DKIM-Signature: v=1; a=ed25519-sha256; s=202507e; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1789588935; bh=1OXxOnbJI64tKjJBlcCcfNg /vmHmtRmMcXj4ssSqyI8=; b=uI3PUxmRuoMkYc14i+UHDku63fW62n8nkas/svUZhCU0d/DWk0 TsjJew1QWX6XuXf9vkWZTCLMrkejqMK85fDg==; From: Bradley Morgan To: Andrew Morton , Vineet Gupta , Guo Ren , Yoshinori Sato , Rich Felker , Chris Zankel , Max Filippov Cc: Arnd Bergmann , "Paul E . McKenney" , David Laight , John Paul Adrian Glaubitz , linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org, Bradley Morgan Subject: [PATCH v2 2/5] ARC: Emulate two-byte cmpxchg Date: Wed, 16 Sep 2026 20:02:12 +0000 Message-ID: <20260916200215.21774-3-brads@mainlining.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260916200215.21774-1-brads@mainlining.org> References: <20260916200215.21774-1-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 ARC has no two-byte atomic compare and swap, so the __cmpxchg() macro switch lets case 2 fall through to BUILD_BUG() via default. Route case 2 through the new cmpxchg_emu_u16(), which now takes natural u16 arguments, so the (uintptr_t) casts on _o_ and _n_ become (u16) casts. Signed-off-by: Bradley Morgan --- arch/arc/include/asm/cmpxchg.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h index 76f43db0890f..4451c2011ee3 100644 --- a/arch/arc/include/asm/cmpxchg.h +++ b/arch/arc/include/asm/cmpxchg.h @@ -50,6 +50,9 @@ case 1: \ _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u8((volatile u8 *__force)_p_, (uintptr_t)_o_, (uintptr_t)_n_); \ break; \ + case 2: \ + _prev_ = (__typeof__(*(ptr)))cmpxchg_emu_u16((volatile u16 *__force)_p_, (u16)_o_, (u16)_n_); \ + break; \ case 4: \ _prev_ = __cmpxchg(_p_, _o_, _n_); \ break; \ -- 2.47.3