From nobody Tue Apr 7 12:20:08 2026 Received: from mail-yw1-f176.google.com (mail-yw1-f176.google.com [209.85.128.176]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5A6236AB53 for ; Fri, 3 Apr 2026 15:03:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.176 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775228625; cv=none; b=tmfDASq7rfdDBGlhjarBF3J9RmfOqTgI/We5mo/jLfaLmfWos3GCr3ri4TD8ozjJCssxQI5yrJrFiWTnS08VH922RD4E8tLTrANpBCq491nPVQZMGb+FoGx5mW9FGXEOXjB4r96dEy0epTLkUAQrEjuNe+vlat3a7h7Ba/GwNlg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775228625; c=relaxed/simple; bh=XCMS7k6CgeZB3csy9pq7EvazIKrd5EQdEHXqEzp6Dgo=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=JUL4+8kLEF/agM9omtwFhP+O42oEOfrHnBk+G61hcryxAhkXzVXoCFjYg4A8ymcrgt8Ay9iDuzNVX3L+O4RWaDRmHgQLfpDugTS3Y+2wLfj0mPfZVARJIpJ/sK5PcELw4PHvxxDcmklvyQvkbtTHYCPj8G4bBiFNBFlDwWe4Lsc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=pY0hh1jZ; arc=none smtp.client-ip=209.85.128.176 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pY0hh1jZ" Received: by mail-yw1-f176.google.com with SMTP id 00721157ae682-7a299d84b7dso14957947b3.0 for ; Fri, 03 Apr 2026 08:03:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775228624; x=1775833424; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=M8bplD3jbYsbQWbLfaU5uM/qKEGJ+sbfo/352EZGhsM=; b=pY0hh1jZgn/qfOL5IACPE4ImcNhfj6GibNCC1fwUNWyCjgq98NDxKZWW6FTu5O8Fhk ZP/kdldVZhZ/6HxywWzy4NmtaTfCsGseAFYZwZ3/z54sxR3dAYn+2FMtd2/DjkJXBR3Q GlQ80w03dPM+vzHZbFJeROA/7s3ZBdedtsvno8ROn8wd4mRzFdHPpiFMJc8Sm8X6yx5q JjJ6SlZTXOHC8GwMsSYPRkRkoxJBYAyKywdshUv6xVV2SxEsZi7ws3dt0LKBKZQfxZA3 gnSVFBvtHBlZuRk0Oke17i+nEoI70vsOWM+OXzcAvAAVEskYJKQcb2vQX2lgtx+xSoPC 9xwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775228624; x=1775833424; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=M8bplD3jbYsbQWbLfaU5uM/qKEGJ+sbfo/352EZGhsM=; b=mclppCbhTjEEok1W2SEPhoeGRJDpNrs4GPFGP3l6pw2U97i2HDMtMNoPNQUTb+dZdT aGg/4h7643SonwmqyvmN+Zg0aZYl5aXO9/524HHl1jJFQ6rgC51+RXZQSsMn7PiWGAWB iVMFJms/nEtHfBFl6lp5dVWSgGyre2dhCDDQ7IGVJKWb+YJnsxzEoEPNJbegjMVyPJn0 iZ9KzU6N57uooB1M7nT+xbGFa1mMw9WIc/xhNkFLyJ2o8tgJZF6DCLzl2x8Bw8rhIE7L +K/KXj1So/sgVECrT23kld/EXWxau0oo23CPoYyRGFGQ1KUaI4TTE+u5CavRjn36Z36q EDig== X-Forwarded-Encrypted: i=1; AJvYcCU9Ll4x2XTkekEfIvwIt/uWePhtdOa9SzCpg8Pp1FqXh+/Z4+ruKPhdEfuc4EF9Gy6kLyVjCvq21Ico4r4=@vger.kernel.org X-Gm-Message-State: AOJu0YwupKLn0ewYVRNlx1+9lgLtpW3rLZ7EJvIqgfMozWmW9X0UyTxZ UlvuPQwR7wpHJEosdn+GhKsRykfPLxUxYj5F8N0meB4b7XpZF9HfjjiE X-Gm-Gg: AeBDieucOM1nXwG2LdM6WezXfKtS7Nec0xDd/NVvpS5a5MkrF/8suKd7skWUxlYem/i Ufshyk8oh1Rj2NPG3GCEDhCErVZp13vxL7lobSwQbfVpULxVUCmrTWtWPEgwUU5YTtjsLBbyd2z SZfcXPnECgN6TdG9m0vmENr4wBPNh2YIVaVcwac8SAgzpiH/Pk2fRfekuPJK2y+CARVc4LczYFR JMhpda1FQbfo+tL4Y9UnRy1qjwJXwOmOTxRLRAUjWT45tflsUFEXKsPO/0q8miZ4QCIlBe+y2fs 2HgTwz+aeFEI+IUZCu3u2+0gxL3fsO7DR1uFUQuXz5M81Q54hyS3kTC906RrcHC3/VTImif+tVm fyxhkiZkJW6VXX4mJjtSMEfbuAzwE3PL5VXmvRglN5BbWFsNLgY8l84NhhkLs+TMJXY4HVqX6bd YT+5BLKgLbANZLYz15H8w= X-Received: by 2002:a05:690c:e3ee:b0:79f:16d7:1d7a with SMTP id 00721157ae682-7a4d5f552efmr34586707b3.43.1775228623644; Fri, 03 Apr 2026 08:03:43 -0700 (PDT) Received: from localhost ([76.195.202.134]) by smtp.gmail.com with UTF8SMTPSA id 00721157ae682-7a3709075besm22398287b3.25.2026.04.03.08.03.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 03 Apr 2026 08:03:42 -0700 (PDT) From: Matt Turner To: Magnus Lindholm Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, Matt Turner Subject: [PATCH] alpha: Select ARCH_SUPPORTS_ATOMIC_RMW Date: Fri, 3 Apr 2026 11:03:29 -0400 Message-ID: <20260403150340.489381-1-mattst88@gmail.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Alpha has native LL/SC instructions (LDL_L/STL_C, LDQ_L/STQ_C) that provide atomic read-modify-write capability, and already selects ARCH_HAVE_NMI_SAFE_CMPXCHG. Selecting ARCH_SUPPORTS_ATOMIC_RMW enables MUTEX_SPIN_ON_OWNER and RWSEM_SPIN_ON_OWNER on SMP, allowing optimistic spinning on contended locks rather than immediately sleeping. Assisted-by: Claude:claude-opus-4-6 Signed-off-by: Matt Turner --- arch/alpha/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git ./arch/alpha/Kconfig ./arch/alpha/Kconfig index 4329743757e3..57c91ed67b71 100644 --- ./arch/alpha/Kconfig +++ ./arch/alpha/Kconfig @@ -10,6 +10,7 @@ config ALPHA select ARCH_MODULE_NEEDS_WEAK_PER_CPU if SMP select ARCH_NO_PREEMPT select ARCH_NO_SG_CHAIN + select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_PAGE_TABLE_CHECK select ARCH_USE_CMPXCHG_LOCKREF select FORCE_PCI --=20 2.52.0