From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1545C98307 for ; Tue, 22 Sep 2026 17:36:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=boUPUsy7ZECMGqiQ355v+ofcH2XXYmrH2JdY4f+tCk4=; b=jAbEqVQ++92BVY rM0mxen+HVv//klT+0qC3lG0o7860pRntICfEWsK9ivWgVq8lIM2Cz2Of5xInCc7UHwO6lh8LU4nu 0uo+g30r9pSnasscWRxHwP0P0qTiCzr/fYQiCgAQFajpqjyjuYbe8NUZ7Z7COjNIbGeAwCQtPCewi mwcSzllIgSuZ/5xQU44qKidWf94eH7vSRtOyhisLbCONP/rqqbN0M2ego5Du+8RyEFY3KY5RZy3of f9Z8NpXeKgzSYiBEkW7iyjpZVbLkkHG0ntUZKS0y54rnvvjbQjShV73PoFT7O3OrvORoivZjytvrV Jo+7pAnjPFpCEbZbHNsA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x94Pr-00000006Dw0-22FM; Tue, 22 Sep 2026 17:36:27 +0000 Received: from mail.mainlining.org ([5.75.144.95]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x94Po-00000006DuK-0nDY for linux-snps-arc@lists.infradead.org; Tue, 22 Sep 2026 17:36:25 +0000 DKIM-Signature: v=1; a=rsa-sha256; s=202507r; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1790098435; bh=4wVfAlEcovYJiLRAiW1UExN eq/b3xEK1OUjxcP/7QYQ=; b=hxyhNKhpHnG4LHB+IQytsfxPMEf6YigYhmBGZ6P1fc8JdTpofF 6/G3CK5eZbESW1khN3Oxuk3tTVRtyjIbZxXm7V/HRQMWqDGh17DVaXZRIj+dplFovWqMFx6Qd/N HYEuhDiGM8wwpRWslxqJozCj/owYlqjVph49yfKRkBOvKGP/olaRr80OLt3TX6jlUFhNPfXQASk UQuRL00HYhzZ/jl7YWoEfFoMh0jYwokqxLaO14TRt4zS0R4tL5JIgaJwdbMzvfPphucuTBMnKFP jjNQE9iV8ZIxOPszyZmfCQkHSxGLynC1RjC3MsaMYSL/3LD5RIP4ZC1boH5HOoZSaVw==; DKIM-Signature: v=1; a=ed25519-sha256; s=202507e; d=mainlining.org; c=relaxed/relaxed; h=Message-ID:Date:Subject:To:From; t=1790098435; bh=4wVfAlEcovYJiLRAiW1UExN eq/b3xEK1OUjxcP/7QYQ=; b=mIt3IqqSgxeINDfPOkt7tdWMzH4kExoyXkiMgmIYJl8N/S4dZ9 2BgUIRlcxsvR2j6OPj3KfJzB0NPulRzvSkDg==; 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 5/5] xtensa: Emulate two-byte cmpxchg Date: Tue, 22 Sep 2026 17:33:54 +0000 Message-ID: <20260922173354.14404-6-brads@mainlining.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260922173354.14404-1-brads@mainlining.org> References: <20260922173354.14404-1-brads@mainlining.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_103624_378749_03DEAC40 X-CRM114-Status: GOOD ( 10.07 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org 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, so the (unsigned long) casts on _o_ and _n_ move off the call and into _old_ and _new_ declarations that type check the old and new arguments against *ptr through (unsigned long)(0 ? *ptr : (o)), the idiom David Laight suggested, so cmpxchg(&p, 4, 5) no longer compiles silently. Signed-off-by: Bradley Morgan --- arch/xtensa/include/asm/cmpxchg.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h index b6db4838b175..f6bed4221b43 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; @@ -83,10 +84,10 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size) } #define arch_cmpxchg(ptr,o,n) \ - ({ __typeof__(*(ptr)) _o_ = (o); \ - __typeof__(*(ptr)) _n_ = (n); \ - (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \ - (unsigned long)_n_, sizeof (*(ptr))); \ + ({ unsigned long _old_ = (unsigned long)(0 ? *(ptr) : (o)); \ + unsigned long _new_ = (unsigned long)(0 ? *(ptr) : (n)); \ + (__typeof__(*(ptr))) __cmpxchg((ptr), _old_, \ + _new_, sizeof (*(ptr))); \ }) #include -- 2.47.3 _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc