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 E5C264078E1; Fri, 11 Sep 2026 19:25:57 +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=1789154765; cv=none; b=F5ap54l68Vb76PgeIwqjPB3n+6O599Dh5/eMBw+I7USS0rnw5CjDh0gC0oFZUHXuEoHmA/tuQwTx7xO4e7pAIFen8x7WGdiKmoBtMJ5Te/XgDd4ZGpcMLQOILJ2skGV5UeDrT+Nu2dyhZa9m3Xbxt/upxAPOX803XbnJWawFl/U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789154765; c=relaxed/simple; bh=GB1GwFjqXeqizek/00dnvDkz0F+QNMMfI6yJw319v/I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=k/bOtHdbnSqpAEywLHkIvfIn1yI09t+t+hottSwFoyGZXQ4GJLg3mnAHISyr4JGSHkpV6nNhWPxROw/5BY/ZB1wJ5K8CglLe7QCdVaZnxGIH7tdcAkbC7pMn6z3jNmrPtF3N56+lSuHseJB9VDw9DtDMZ333gz+70T5HOE2dKxU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mainlining.org; spf=pass smtp.helo=mail.mainlining.org; 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.helo=mail.mainlining.org From: Bradley Morgan To: "Paul E. McKenney" Cc: frederic@kernel.org, neeraj.upadhyay@kernel.org, boqun@kernel.org, joelagnelf@nvidia.com, rcu@vger.kernel.org, "Andrew Morton" , "Arnd Bergmann" , linux-arch@vger.kernel.org, "Vineet Gupta" , linux-snps-arc@lists.infradead.org, "Russell King" , linux-arm-kernel@lists.infradead.org, "Guo Ren" , linux-csky@vger.kernel.org, "Yoshinori Sato" , "Rich Felker" , "John Paul Adrian Glaubitz" , linux-sh@vger.kernel.org, "Chris Zankel" , "Max Filippov" , linux-kernel@vger.kernel.org, brads@mainlining.org Subject: [PATCH 6/6] xtensa: Emulate two-byte cmpxchg Date: Fri, 11 Sep 2026 19:25:39 +0000 Message-ID: <20260911192540.20983-7-brads@mainlining.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260911192540.20983-1-brads@mainlining.org> References: <20260911192540.20983-1-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 byte or halfword atomic memory operations, so the __cmpxchg() switch routes case 1 through cmpxchg_emu_u8() and lets case 2 hit the default, __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(). 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; -- 2.47.3