Date:   Thu, 9 Feb 2023 11:24:13 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Oleksandr Tyshchenko <olekstysh@gmail.com>
Cc:     xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>
Subject: Re: [PATCH] xen/grant-dma-iommu: Implement a dummy probe_device()
 callback
Message-ID: <20230209055413.k2jbmqvqg636jrgw@vireshk-i7>
References: <20230208153649.3604857-1-olekstysh@gmail.com>
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On 08-02-23, 17:36, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> Update stub IOMMU driver (which main purpose is to reuse generic
> IOMMU device-tree bindings by Xen grant DMA-mapping layer on Arm)
> according to the recent changes done in the following
> commit 57365a04c921 ("iommu: Move bus setup to IOMMU device registration").
> 
> With probe_device() callback being called during IOMMU device registration,
> the uninitialized callback just leads to the "kernel NULL pointer
> dereference" issue during boot. Fix that by adding a dummy callback.
> 
> Looks like the release_device() callback is not mandatory to be
> implemented as IOMMU framework makes sure that callback is initialized
> before dereferencing.
> 
> Reported-by: Viresh Kumar <viresh.kumar@linaro.org>
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> ---
>  drivers/xen/grant-dma-iommu.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)

Tested-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh