linux-kernel - Re: [PATCH] iommu: Don't call .probe

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Message-ID: <1589957603.13912.2.camel@mhfsdcap03>
Date:   Wed, 20 May 2020 14:53:23 +0800
From:   Yong Wu <yong.wu@...iatek.com>
To:     Joerg Roedel <joro@...tes.org>
CC:     <iommu@...ts.linux-foundation.org>, Joerg Roedel <jroedel@...e.de>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [PATCH] iommu: Don't call .probe_finalize() under group->mutex

On Tue, 2020-05-19 at 15:28 +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@...e.de>
> 
> The .probe_finalize() call-back of some IOMMU drivers calls into
> arm_iommu_attach_device(). This function will call back into the
> IOMMU core code, where it tries to take group->mutex again, resulting
> in a deadlock.
> 
> As there is no reason why .probe_finalize() needs to be called under
> that mutex, move it after the lock has been released to fix the
> deadlock.
> 
> Cc: Yong Wu <yong.wu@...iatek.com>
> Reported-by: Yong Wu <yong.wu@...iatek.com>
> Fixes: deac0b3bed26 ("iommu: Split off default domain allocation from group assignment")
> Signed-off-by: Joerg Roedel <jroedel@...e.de>

Tested-by: Yong Wu <yong.wu@...iatek.com>

Tested on MediaTek-v1 mt2701 evb board.