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Date:   Wed, 5 Apr 2023 03:33:22 +0300
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Subject: Re: [PATCH v1 5/7] Revert "drm: Assert held reservation lock for
 dma-buf mmapping"
To:     =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Benjamin Gaignard <benjamin.gaignard@collabora.com>,
        Liam Mark <lmark@codeaurora.org>,
        Brian Starkey <Brian.Starkey@arm.com>,
        John Stultz <jstultz@google.com>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Tomi Valkeinen <tomba@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        Amol Maheshwari <amahesh@qti.qualcomm.com>,
        Emil Velikov <emil.l.velikov@gmail.com>
Cc:     linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org,
        linux-tegra@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        kernel@collabora.com
References: <20230402164826.752842-1-dmitry.osipenko@collabora.com>
 <20230402164826.752842-6-dmitry.osipenko@collabora.com>
 <7854897f-67f8-e82c-3edf-e8ef923d2474@amd.com>
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From:   Dmitry Osipenko <dmitry.osipenko@collabora.com>
In-Reply-To: <7854897f-67f8-e82c-3edf-e8ef923d2474@amd.com>
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On 4/3/23 18:17, Christian König wrote:
> Am 02.04.23 um 18:48 schrieb Dmitry Osipenko:
>> Don't assert held dma-buf reservation lock on memory mapping of exported
>> buffer.
>>
>> We're going to change dma-buf mmap() locking policy such that exporters
>> will have to handle the lock. The previous locking policy caused deadlock
>> problem for DRM drivers in a case of self-imported dma-bufs, it's solved
>> by moving the lock down to exporters.
> 
> I only checked the TTM code path and think that at least that one should
> work fine.
> 
>> Fixes: 39ce25291871 ("drm: Assert held reservation lock for dma-buf
>> mmapping")
> 
> This here is not really a "fix" for the previous patch. We just found
> that we didn't like the behavior and so reverted the original patch.
> 
> A "Reverts..." comment in the commit message would be more appropriate I
> think.

Ack, will drop the fixes tag in v2. Thank you and Emil for the review.

-- 
Best regards,
Dmitry