linux-kernel - Re: [PATCH v9 5/9] x86/resctrl: Unwind the errors inside rdt_enable

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Message-ID: <b22da35c-ceeb-7116-b33d-4e596980bf80@intel.com>
Date:   Mon, 11 Sep 2023 15:58:06 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Babu Moger <babu.moger@....com>, <corbet@....net>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>
CC:     <fenghua.yu@...el.com>, <dave.hansen@...ux.intel.com>,
        <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
        <akpm@...ux-foundation.org>, <quic_neeraju@...cinc.com>,
        <rdunlap@...radead.org>, <damien.lemoal@...nsource.wdc.com>,
        <songmuchun@...edance.com>, <peterz@...radead.org>,
        <jpoimboe@...nel.org>, <pbonzini@...hat.com>,
        <chang.seok.bae@...el.com>, <pawan.kumar.gupta@...ux.intel.com>,
        <jmattson@...gle.com>, <daniel.sneddon@...ux.intel.com>,
        <sandipan.das@....com>, <tony.luck@...el.com>,
        <james.morse@....com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <bagasdotme@...il.com>,
        <eranian@...gle.com>, <christophe.leroy@...roup.eu>,
        <jarkko@...nel.org>, <adrian.hunter@...el.com>,
        <quic_jiles@...cinc.com>, <peternewman@...gle.com>
Subject: Re: [PATCH v9 5/9] x86/resctrl: Unwind the errors inside
 rdt_enable_ctx()

Hi Babu,

On 9/7/2023 4:51 PM, Babu Moger wrote:
> rdt_enable_ctx() enables the features provided during resctrl mount.
> 
> Additions to rdt_enable_ctx() are required to also modify error paths
> of rdt_enable_ctx() callers to ensure correct unwinding if errors
> are encountered after calling rdt_enable_ctx(). This is error prone.
> 
> Introduce rdt_disable_ctx() to refactor the error unwinding of
> rdt_enable_ctx() to simplify future additions. This also simplifies
> cleanup in rdt_kill_sb().
> 
> Remove cdp_disable_all() as it is not used anymore after the refactor.
> 
> Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
> Reviewed-by: Fenghua Yu <fenghua.yu@...el.com>
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---

This is one of the patches that received a change that was not
mentioned in cover letter nor in a patch specific list of changes.

Having a list of changes within each patch in this area is
helpful in reviews.

>  arch/x86/kernel/cpu/resctrl/rdtgroup.c | 55 ++++++++++++++++----------
>  1 file changed, 34 insertions(+), 21 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> index 35945b4bf196..34cb512be1de 100644
> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
> @@ -2290,14 +2290,6 @@ int resctrl_arch_set_cdp_enabled(enum resctrl_res_level l, bool enable)
>  	return 0;
>  }
>  
> -static void cdp_disable_all(void)
> -{
> -	if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L3))
> -		resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
> -	if (resctrl_arch_get_cdp_enabled(RDT_RESOURCE_L2))
> -		resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
> -}
> -
>  /*
>   * We don't allow rdtgroup directories to be created anywhere
>   * except the root directory. Thus when looking for the rdtgroup
> @@ -2377,19 +2369,44 @@ static int mkdir_mondata_all(struct kernfs_node *parent_kn,
>  			     struct rdtgroup *prgrp,
>  			     struct kernfs_node **mon_data_kn);
>  
> +static void rdt_disable_ctx(void)
> +{
> +	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L3, false);
> +
> +	resctrl_arch_set_cdp_enabled(RDT_RESOURCE_L2, false);
> +
> +	set_mba_sc(false);
> +}

Could you please remove the empty line following each call?

With the above change you can add:

Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette