linux-kernel - Re: [PATCH v11 05/10] x86/resctrl: Unwind the errors inside rdt_enable

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Date:   Mon, 9 Oct 2023 10:59:27 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Borislav Petkov <bp@...en8.de>, Babu Moger <babu.moger@....com>
CC:     <corbet@....net>, <tglx@...utronix.de>, <mingo@...hat.com>,
        <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 v11 05/10] x86/resctrl: Unwind the errors inside
 rdt_enable_ctx()

Hi Boris,

On 10/9/2023 10:25 AM, Borislav Petkov wrote:
> On Tue, Oct 03, 2023 at 06:54:25PM -0500, 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.
> 
> Do not talk about *what* the patch is doing in the commit message - that
> should be obvious from the diff itself. Rather, concentrate on the *why*
> it needs to be done.

I worked with Babu on this commit message and would appreciate guidance to
get this (and others) right. The second paragraph intends to explain the
current problem with rdt_enable_ctx() with the third paragraph providing an
overview of how the problem will be fixed and why (future code needs to touch
this area).

Is it the fourth paragraph (mentioning cdp_disable_all()) that is annoying? I
can see that it is redundant. Would it be more palatable if the fourth paragraph
is just dropped?

> 
> Check your whole series.
> 

Reinette