linux-kernel - Re: [Patch v2 3/3] iommu: avoid taking iova_rbtree

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Message-ID: <CAM_iQpXznBnh+bVMu4Ad-doPfr7en9CnWiG8C8mEXmYu6yTgxg@mail.gmail.com>
Date:   Fri, 29 Nov 2019 22:03:45 -0800
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     John Garry <john.garry@...wei.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice

On Fri, Nov 29, 2019 at 5:34 AM John Garry <john.garry@...wei.com> wrote:
>
> On 29/11/2019 00:48, Cong Wang wrote:
> > Both find_iova() and __free_iova() take iova_rbtree_lock,
> > there is no reason to take and release it twice inside
> > free_iova().
> >
> > Fold them into the critical section by calling the unlock
> > versions instead.
>
> Since generally the iova would be non-NULL, this seems a reasonable
> change (which could be mentioned in the commit log)

I think it is too obvious to mention it. There are many things we can
mention but we should only mention what's necessary, right?

Thanks.