linux-kernel - Re: [RFC 0/3] iommu/iova: Unsafe locking in find

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Message-ID: <CAJwJo6Z8jGFdb0ZEUNFt+T7HiLvS69w6_QC9qVs9TqiJ7+sjTw@mail.gmail.com>
Date:   Tue, 3 Jul 2018 19:59:20 +0100
From:   Dmitry Safonov <0x7f454c46@...il.com>
To:     Dmitry Safonov <dima@...sta.com>
Cc:     open list <linux-kernel@...r.kernel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org
Subject: Re: [RFC 0/3] iommu/iova: Unsafe locking in find_iova()

Hi,

Any opinion on that?
It looks to remove a source of possible issues and
has a nice diffstat.

2018-06-21 19:08 GMT+01:00 Dmitry Safonov <dima@...sta.com>:
> find_iova() looks to be using a bad locking practice: it locks the
> returned iova only for the search time.
> And looking in code, the element can be removed from the tree and freed
> under rbtree lock. That happens during memory hot-unplug and cleanup on
> module removal.
> Here I cleanup users of the function and delete it.
>
> Dmitry Safonov (3):
>   iommu/iova: Find and split iova under rbtree's lock
>   iommu/iova: Make free_iova() atomic
>   iommu/iova: Remove find_iova()
>
>  drivers/iommu/intel-iommu.c | 14 +++----------
>  drivers/iommu/iova.c        | 48 +++++++++++++++++----------------------------
>  include/linux/iova.h        | 17 ++++------------
>  3 files changed, 25 insertions(+), 54 deletions(-)
>

Thanks,
             Dmitry