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Sat, 05 Sep 2026 12:29:38 -0700 (PDT) Received: from localhost ([2600:1702:7a90:6f9f:8bc4:8aec:108d:7a04]) by smtp.gmail.com with ESMTPSA id 956f58d0204a3-66fb47a8894sm5071491d50.1.2026.09.05.12.29.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Sep 2026 12:29:37 -0700 (PDT) From: Matt Turner Date: Sat, 05 Sep 2026 15:29:27 -0400 Subject: [PATCH v2 06/22] alpha: select ARCH_SUPPORTS_ATOMIC_RMW Precedence: bulk X-Mailing-List: linux-alpha@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260905-arch-kconfig-options-v2-v2-6-83e8245761a2@gmail.com> References: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> In-Reply-To: <20260905-arch-kconfig-options-v2-v2-0-83e8245761a2@gmail.com> To: Richard Henderson , Magnus Lindholm , Kees Cook , Marco Elver , Andrey Konovalov , Andrey Ryabinin , Jonathan Corbet , Shuah Khan , Randy Dunlap Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org, linux-doc@vger.kernel.org, Matt Turner X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=1013; i=mattst88@gmail.com; h=from:subject:message-id; bh=q2x0WUHz2r8ueAKqk8Cn9VqXFBZAzyHK+DfKvxu66yg=; b=owGbwMvMwCW25rVmCc8sv+mMp9WSGLLm5E6WtGqS3pvKJfx1ye9TR9bu+rTb+tTCMxrC0+Nqr zmERf541/GRhUGMi2GmmCJL3HpFllltO5b6nJb+BTOHlQlkiLRIAwMQsDDw5SbmlRrpGOmZahvq GQIZOkbxEDk9Bo3M4uLS1CLdtIIih7z8ksSSzPy8Yr38gtS8gvQCvbTMtJKMjPyi4lSgEXp5qSW mro5uRoYGJpaOFmZOFo6mJs7OToZObo6Ozq5ORpbmJgbOlo4mrpbmDFycAjDXMB1g+B/0deOFT/ cfTA/8meDMFqTk8UHidPbMADf35Qc2X5RSue3EyHD2pv70ieHKQsd6TS+0Cqa5n4zMteB/1iYnt Z49VK/yAgsA X-Developer-Key: i=mattst88@gmail.com; a=openpgp; fpr=3BB639E56F861FA2E86505690FDD682D974CA72A 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 Tested-by: Magnus Lindholm Reviewed-by: Magnus Lindholm --- arch/alpha/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 032c23f979c4..d039b7135d18 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -14,6 +14,7 @@ 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_USE_CMPXCHG_LOCKREF select FORCE_PCI select PCI_DOMAINS if PCI -- 2.54.0