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

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Message-ID: <1531159069.3205.63.camel@arista.com>
Date:   Mon, 09 Jul 2018 18:57:49 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     linux-kernel@...r.kernel.org,
        David Woodhouse <dwmw2@...radead.org>,
        iommu@...ts.linux-foundation.org,
        Dmitry Safonov <0x7f454c46@...il.com>
Subject: Re: [RFC 0/3] iommu/iova: Unsafe locking in find_iova()

On Fri, 2018-07-06 at 17:13 +0200, Joerg Roedel wrote:
> On Fri, Jul 06, 2018 at 03:10:47PM +0100, Dmitry Safonov wrote:
> > Yes, as far as I can see, there are code-paths which may try to
> > handle
> > it at the same time:
> > o memory notifiers for hot-unplug (intel-iommu.c)
> > o drivers unloading calls free_iova(), which in the result calls
> >   find_iova()
> > o I see at least one driver that frees iova during it's normal work
> >   too: scif_rma.c:scif_free_window_offset()
> 
> Yeah, but the IOVAs freed in the memory notifiers are just the ones
> for
> the direct-mapped RMRR regions requested by firmware, not the IOVAs
> allocated by any driver, so I think this shouldn't be a problem.

Ok, than drop it, please.
I thought that safer API + nice diffstat can justify the change, but
whatever %)

-- 
Thanks,
             Dmitry