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 06D31CAC5B8 for ; Thu, 2 Oct 2025 18:02:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=3k+J8qpFjK/lgGh7Zl03b2mMgOSIB2yOErhlwgHFOls=; b=NHRz1lDj1k5vNHO2e1A4LBuqql O5b0yd4CUDOS//AyIE2VXXg7XtqXJB2v43mYbDIu5AuxcKmq9QrHJuO++o0VTzCL8B1NmD6mmZKSf t3ozT4qf485L3Ijsc0x7puGEQ+uaEz1rSaD8eW5atPLk7vA2ksUaaZ2iYOsO00jYNWFQ9z+wq5vV9 q3T8eMyeSMQlEPLuCM1o25uLNi0nUqFRBVj9jRoH1gzrwZOb3NA0U/MMZXbYfqe9/yddRvHb34t+U gX3Qhsdjsg0vCTHYICMK9h4PxcuCAlB4Ep898cqLA5Ddn46SEukWwrjz7xpfkW/VNhP/2Qnx2ZbnW KT9tyW6A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v4NdO-0000000Axw8-42lj; Thu, 02 Oct 2025 18:02:30 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1v4NdL-0000000Axty-1mKX for linux-arm-kernel@lists.infradead.org; Thu, 02 Oct 2025 18:02:29 +0000 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 006BE1FCD; Thu, 2 Oct 2025 11:02:16 -0700 (PDT) Received: from [10.1.197.69] (eglon.cambridge.arm.com [10.1.197.69]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EF10D3F66E; Thu, 2 Oct 2025 11:02:18 -0700 (PDT) Message-ID: <2c5c6e2a-e0ea-4786-ba6e-2c536a53a68b@arm.com> Date: Thu, 2 Oct 2025 19:02:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 17/29] arm_mpam: Extend reset logic to allow devices to be reset any time To: Ben Horgan , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org Cc: D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com, dfustini@baylibre.com, amitsinght@marvell.com, David Hildenbrand , Dave Martin , Koba Ko , Shanker Donthineni , fenghuay@nvidia.com, baisheng.gao@unisoc.com, Jonathan Cameron , Rob Herring , Rohit Mathew , Rafael Wysocki , Len Brown , Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla , Catalin Marinas , Will Deacon , Greg Kroah-Hartman , Danilo Krummrich References: <20250910204309.20751-1-james.morse@arm.com> <20250910204309.20751-18-james.morse@arm.com> <9fa1b584-130b-45b0-9dba-8e046e643bf0@arm.com> Content-Language: en-GB From: James Morse In-Reply-To: <9fa1b584-130b-45b0-9dba-8e046e643bf0@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251002_110227_509352_3198E9C8 X-CRM114-Status: GOOD ( 16.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Ben, On 12/09/2025 12:42, Ben Horgan wrote: > On 9/10/25 21:42, James Morse wrote: >> cpuhp callbacks aren't the only time the MSC configuration may need to >> be reset. Resctrl has an API call to reset a class. >> If an MPAM error interrupt arrives it indicates the driver has >> misprogrammed an MSC. The safest thing to do is reset all the MSCs >> and disable MPAM. >> >> Add a helper to reset RIS via their class. Call this from mpam_disable(), >> which can be scheduled from the error interrupt handler. >> diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c >> index e7faf453b5d7..a9d3c4b09976 100644 >> --- a/drivers/resctrl/mpam_devices.c >> +++ b/drivers/resctrl/mpam_devices.c >> @@ -842,8 +842,6 @@ static int mpam_reset_ris(void *arg) >> u16 partid, partid_max; >> struct mpam_msc_ris *ris = arg; >> >> - mpam_assert_srcu_read_lock_held(); >> - > > Remove where it is introduced. There is already one in > mpam_reset_ris_partid() at that time. Mmmm, this should really have been replaced with a comment. I prefer each function to have an assert like this as documentation. In this case, a new caller may miss the lock, but always hit the 'in_reset_state' case during testing, and be caught out when a call to mpam_reset_ris_partid() occurs. Having documentation comments that can also bark at you when you ignore them is really handy! It's removed in this patch because calling it via mpam_touch_msc() puts it behind an call to schedule, and lockdep expects 'current' to be the one holding the lock. I'll add the comment. Looks like it just got dropped when mpam_touch_msc() stopped using an IPI... >> if (ris->in_reset_state) >> return 0; > > Reviewed-by: Ben Horgan Thanks! James