From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0B19F275AE4; Thu, 2 Oct 2025 18:02:24 +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=1759428146; cv=none; b=q4h0ynemZMT9hc076y7Drky4zGoydi3AemVwsBq8CzDmFnJD+1eruj+RiL1NlmKlenbNtkgt4/UZvenFJiN4o/OgOG4HyB9WjDQUVZ3mbR7qXfe6BQWWpxAoYXwEohxggxnIk9exz+b6l5VODKQVU2KgeyFilwN6QEv01OqYY+M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759428146; c=relaxed/simple; bh=d9JMwz3pZXPH7YSUzmEm3uXPoHX5XC/PPW4BNzQqJCk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=f92e+9Anw8T03m9xynA3Py5vyVGEl3ucyl2jnKlmXNMnOuUgzOvwO/eSJiYVkj9Py0A18ZvjXW17F+/TJ8wHuk0SIygr3cOyNeecH23crse4KK4dgKEvw6Nx7tlSO6YOXDVQL4/3jaeIf1WyN0moN7efO5YzFCJtmJYLWZHAuT8= 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 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 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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