linux-kernel - RE: [PATCH v5 04/21] x86/resctrl: Group struct rdt_hw

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Message-ID: <TYAPR01MB6330E0E18CF4A229B38511648BBB9@TYAPR01MB6330.jpnprd01.prod.outlook.com>
Date:   Wed, 29 Jun 2022 08:33:44 +0000
From:   "tan.shaopeng@...itsu.com" <tan.shaopeng@...itsu.com>
To:     'James Morse' <james.morse@....com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        H Peter Anvin <hpa@...or.com>,
        Babu Moger <Babu.Moger@....com>,
        "shameerali.kolothum.thodi@...wei.com" 
        <shameerali.kolothum.thodi@...wei.com>,
        D Scott Phillips OS <scott@...amperecomputing.com>,
        "lcherian@...vell.com" <lcherian@...vell.com>,
        "bobo.shaobowang@...wei.com" <bobo.shaobowang@...wei.com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Cristian Marussi <cristian.marussi@....com>,
        Xin Hao <xhao@...ux.alibaba.com>,
        "xingxin.hx@...nanolis.org" <xingxin.hx@...nanolis.org>,
        "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>
Subject: RE: [PATCH v5 04/21] x86/resctrl: Group struct rdt_hw_domain cleanup

Hi James,

> domain_add_cpu() and domain_remove_cpu() need to kfree() the child arrays
> that were allocated by domain_setup_ctrlval().
> 
> As this memory is moved around, and new arrays are created, adjusting the
> error handling cleanup code becomes noisier.
> 
> To simplify this, move all the kfree() calls into a domain_free() helper.
> This depends on struct rdt_hw_domain being kzalloc()d, allowing it to
> unconditionally kfree() all the child arrays.
> 
> Reviewed-by: Jamie Iles <quic_jiles@...cinc.com>
> Tested-by: Xin Hao <xhao@...ux.alibaba.com>
> Reviewed-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...itsu.com>
> Tested-by: Cristian Marussi <cristian.marussi@....com>
> Signed-off-by: James Morse <james.morse@....com>
> ---
> Changes since v2:
>  * Made domain_free() static.
> 
> Changes since v1:
>  * This patch is new
> ---
>  arch/x86/kernel/cpu/resctrl/core.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c
> b/arch/x86/kernel/cpu/resctrl/core.c
> index 25f30148478b..e37889f7a1a5 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -414,6 +414,13 @@ void setup_default_ctrlval(struct rdt_resource *r, u32
> *dc, u32 *dm)
>  	}
>  }
> 
> +static void domain_free(struct rdt_hw_domain *hw_dom) {
> +	kfree(hw_dom->ctrl_val);
> +	kfree(hw_dom->mbps_val);
> +	kfree(hw_dom);
> +}
> +
>  static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_domain *d)  {
>  	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r); @@ -488,7
> +495,7 @@ static void domain_add_cpu(int cpu, struct rdt_resource *r)
>  	rdt_domain_reconfigure_cdp(r);
> 
>  	if (r->alloc_capable && domain_setup_ctrlval(r, d)) {
> -		kfree(hw_dom);
> +		domain_free(hw_dom);

domain_free(hw_dom) is executed when fails allocated hw_dom->ctrl_val 
by kmalloc_array() in domain_setup_ctrlval(r, d), 
but hw_dom->ctrl_val is freed in domain_free(hw_dom).

Also, hw_dom->mbps_val is not allocated at this time,
but it is freed in domain_free(hw_dom).

In addition，I tested this patch series on Intel(R) Xeon(R) Gold 6254 CPU with resctrl selftest.
It is no problem.

Best regards,
Shaopeng
>  		return;
>  	}
> 
> @@ -497,9 +504,7 @@ static void domain_add_cpu(int cpu, struct rdt_resource
> *r)
>  	err = resctrl_online_domain(r, d);
>  	if (err) {
>  		list_del(&d->list);
> -		kfree(hw_dom->ctrl_val);
> -		kfree(hw_dom->mbps_val);
> -		kfree(hw_dom);
> +		domain_free(hw_dom);
>  	}
>  }
> 
> @@ -547,12 +552,10 @@ static void domain_remove_cpu(int cpu, struct
> rdt_resource *r)
>  		if (d->plr)
>  			d->plr->d = NULL;
> 
> -		kfree(hw_dom->ctrl_val);
> -		kfree(hw_dom->mbps_val);
>  		bitmap_free(d->rmid_busy_llc);
>  		kfree(d->mbm_total);
>  		kfree(d->mbm_local);
> -		kfree(hw_dom);
> +		domain_free(hw_dom);
>  		return;
>  	}
> 
> --
> 2.30.2