From nobody Tue Feb 10 00:58:34 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0001936998E for ; Mon, 12 Jan 2026 17:00:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768237203; cv=none; b=KAD4g1LMJCsxGxwiupdJJ6sOX1OA8b/vdaeCg3H4jNGSrXOrcFPwwCQLfgvkDQXdAYD8I5ea645vO5PL9SP0Frn8UD40gD8vNWQGYeCRM/Gdl3RkkVGvJOgcSiYz7dpuMX9D4RgCdhvZqbAWobYOW3jkYQ99Wl2Mx7PYb/7xEkg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768237203; c=relaxed/simple; bh=oj4fcTHoEXtPA7MG6nGH+9WSMY2ShQSL6A2VkyhxVJM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=awCokhAMk7AtRUSegK1D8m915rdaURrIjE5KT5DHJYFCZshDBsNbFNjwKfDUY9JgMHS08buduNe2C0Vk7TE2FSsuIjuWDtjewPK6JPXQwCgHmQut9kjXQELrq9nNAKXtYibwYUahWvE0fUtLavn9zwoeriuzQZa0d15fphBCBHo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BC9E3153B; Mon, 12 Jan 2026 08:59:54 -0800 (PST) Received: from e134344.cambridge.arm.com (e134344.arm.com [10.1.196.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5FFA33F694; Mon, 12 Jan 2026 08:59:56 -0800 (PST) From: Ben Horgan To: ben.horgan@arm.com Cc: amitsinght@marvell.com, baisheng.gao@unisoc.com, baolin.wang@linux.alibaba.com, carl@os.amperecomputing.com, dave.martin@arm.com, david@kernel.org, dfustini@baylibre.com, fenghuay@nvidia.com, gshan@redhat.com, james.morse@arm.com, jonathan.cameron@huawei.com, kobak@nvidia.com, lcherian@marvell.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, peternewman@google.com, punit.agrawal@oss.qualcomm.com, quic_jiles@quicinc.com, reinette.chatre@intel.com, rohit.mathew@arm.com, scott@os.amperecomputing.com, sdonthineni@nvidia.com, tan.shaopeng@fujitsu.com, xhao@linux.alibaba.com, catalin.marinas@arm.com, will@kernel.org, corbet@lwn.net, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, suzuki.poulose@arm.com, kvmarm@lists.linux.dev Subject: [PATCH v3 02/47] arm_mpam: Use non-atomic bitops when modifying feature bitmap Date: Mon, 12 Jan 2026 16:58:29 +0000 Message-ID: <20260112165914.4086692-3-ben.horgan@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260112165914.4086692-1-ben.horgan@arm.com> References: <20260112165914.4086692-1-ben.horgan@arm.com> 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" In the test__props_mismatch() kunit test we rely on the struct mpam_props being packed to ensure memcmp doesn't consider packing. Making it packed reduces the alignment of the features bitmap and so breaks a requirement for the use of atomics. As we don't rely on the set/clear of these bits being atomic, just make them non-atomic. Reviewed-by: Jonathan Cameron Signed-off-by: Ben Horgan Reviewed-by: Gavin Shan --- Changes since v2: Add comment (Jonathan) --- drivers/resctrl/mpam_internal.h | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_interna= l.h index 17cdc3080d58..e8971842b124 100644 --- a/drivers/resctrl/mpam_internal.h +++ b/drivers/resctrl/mpam_internal.h @@ -200,8 +200,12 @@ struct mpam_props { } PACKED_FOR_KUNIT; =20 #define mpam_has_feature(_feat, x) test_bit(_feat, (x)->features) -#define mpam_set_feature(_feat, x) set_bit(_feat, (x)->features) -#define mpam_clear_feature(_feat, x) clear_bit(_feat, (x)->features) +/* + * The non-atomic get/set operations are used because if struct mpam_props= is + * packed, the alignment requirements for atomics aren't met. + */ +#define mpam_set_feature(_feat, x) __set_bit(_feat, (x)->features) +#define mpam_clear_feature(_feat, x) __clear_bit(_feat, (x)->features) =20 /* The values for MSMON_CFG_MBWU_FLT.RWBW */ enum mon_filter_options { --=20 2.43.0