linux-kernel - Re: [PATCH 27/33] arm_mpam: Track bandwidth counter state for power management

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Message-ID: <20251110173136.000074ce@huawei.com>
Date: Mon, 10 Nov 2025 17:31:36 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Ben Horgan <ben.horgan@....com>
CC: <james.morse@....com>, <amitsinght@...vell.com>,
	<baisheng.gao@...soc.com>, <baolin.wang@...ux.alibaba.com>,
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	<xhao@...ux.alibaba.com>, Zeng Heng <zengheng4@...wei.com>
Subject: Re: [PATCH 27/33] arm_mpam: Track bandwidth counter state for power
 management

On Fri, 7 Nov 2025 12:34:44 +0000
Ben Horgan <ben.horgan@....com> wrote:

> From: James Morse <james.morse@....com>
> 
> Bandwidth counters need to run continuously to correctly reflect the
> bandwidth.
> 
> Save the counter state when the hardware is reset due to CPU hotplug.
> Add struct mbwu_state to track the bandwidth counter. Support for
> tracking overflow with the same structure will be added in a
> subsequent commit.
> 
> Cc: Zeng Heng <zengheng4@...wei.com>
> Signed-off-by: James Morse <james.morse@....com>
> Signed-off-by: Ben Horgan <ben.horgan@....com>

One trivial below.
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>

>  
> diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
> index d8f8e29987e0..1f2b04b7703e 100644
> --- a/drivers/resctrl/mpam_internal.h
> +++ b/drivers/resctrl/mpam_internal.h
> @@ -91,7 +91,10 @@ struct mpam_msc {
>  	 */
>  	struct mutex		part_sel_lock;
>  
> -	/* cfg_lock protects the msc configuration. */
> +	/*
> +	 * cfg_lock protects the msc configuration and guards against mbwu_state
> +	 * and save and restore racing.

Stray "and" that isn't needed on this second line.

> +	 */
>  	struct mutex		cfg_lock;
>