linux-kernel - Re: [PATCH 2/2] xen/virtio: Fix potential deadlock when accessing xen_grant_dma

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Message-ID: <d1f39ce3-fe09-d3b0-fa6d-01345d1d0429@suse.com>
Date:   Thu, 6 Oct 2022 07:08:30 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Oleksandr Tyshchenko <olekstysh@...il.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Stefano Stabellini <sstabellini@...nel.org>
Subject: Re: [PATCH 2/2] xen/virtio: Fix potential deadlock when accessing
 xen_grant_dma_devices

On 05.10.22 19:48, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> 
> As find_xen_grant_dma_data() is called from both interrupt and process
> contexts, the access to xen_grant_dma_devices XArray must be protected
> by xa_lock_irqsave to avoid deadlock scenario.
> As XArray API doesn't provide xa_store_irqsave helper, call lockless
> __xa_store directly and guard it externally.
> 
> Also move the storage of the XArray's entry to a separate helper.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> Fixes: d6aca3504c7d ("xen/grant-dma-ops: Add option to restrict memory access under Xen")

Reviewed-by: Juergen Gross <jgross@...e.com>


Juergen

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