linux-kernel - Re: [PATCH -v12 01/15] resources: Split out __allocate

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Date:	Tue, 26 Jun 2012 13:33:40 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Tony Luck <tony.luck@...el.com>,
	David Miller <davem@...emloft.net>, x86 <x86@...nel.org>,
	Dominik Brodowski <linux@...inikbrodowski.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH -v12 01/15] resources: Split out __allocate_resource()

On Tue, Jun 26, 2012 at 12:01 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Tue, Jun 26, 2012 at 11:53 AM, Yinghai Lu <yinghai@...nel.org> wrote:
>> It will take bool lock, so we could use it in other functions that
>> hold the resource lock already.
>
> This is too damn ugly.
>
> These kinds of "conditionally take lock" things are always just bugs
> waiting to happen. Don't do it.
>
> Just make the rule be that the caller of the __allocate_resource
> helper has to hold the lock. Sure, that means that you need to then
> use split reallocate_resource() into a helper function (ie a static
> __reallocate_resource() that needs to have the lock taken by the
> caller too), but dammit, that's definitely the right thing to do
> anyway.
>
> These kinds of "bool lock" crap things have to die. They are *wrong*.
> They are a sign of bad locking rules.

You are right, please check updated one.

Thanks

Yinghai

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