linux-kernel - Re: [PATCH] x86/resctrl: Fix potential lockdep warning

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Message-ID: <20191118150240.GF6363@zn.tnic>
Date:   Mon, 18 Nov 2019 16:02:40 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Xiaochen Shen <xiaochen.shen@...el.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        tony.luck@...el.com, fenghua.yu@...el.com,
        reinette.chatre@...el.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, pei.p.jia@...el.com
Subject: Re: [PATCH] x86/resctrl: Fix potential lockdep warning

On Sun, Nov 17, 2019 at 12:13:20AM +0800, Xiaochen Shen wrote:
> Actually this fix covers all the cases of an audit of the calling paths
> of rdt_last_cmd_{clear,puts,printf}(), to make sure we only have the
> lockdep_assert_held() in places where we are sure that it must be held.

That's kinda what I suggested, isn't it?

All I meant was, not to have a

	rdtgroup_kn_lock_live()

call in the code as this function does *not* unconditionally grab the
rdtgroup_mutex. And then call a function which unconditionally checks
whether the mutex is held.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette