linux-kernel - [PATCH v1 3/7] Revert "udmabuf: Assert held reservation lock for dma-buf mmapping"

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Message-Id: <20230402164826.752842-4-dmitry.osipenko@collabora.com>
Date:   Sun,  2 Apr 2023 19:48:22 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Liam Mark <lmark@...eaurora.org>,
        Brian Starkey <Brian.Starkey@....com>,
        John Stultz <jstultz@...gle.com>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Tomi Valkeinen <tomba@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>
Cc:     linux-media@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, intel-gfx@...ts.freedesktop.org,
        linux-tegra@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        kernel@...labora.com
Subject: [PATCH v1 3/7] Revert "udmabuf: Assert held reservation lock for dma-buf mmapping"

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.

Fixes: aa3f99896443 ("udmabuf: Assert held reservation lock for dma-buf mmapping")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
 drivers/dma-buf/udmabuf.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
index 740d6e426ee9..277f1afa9552 100644
--- a/drivers/dma-buf/udmabuf.c
+++ b/drivers/dma-buf/udmabuf.c
@@ -52,8 +52,6 @@ static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma)
 {
 	struct udmabuf *ubuf = buf->priv;
 
-	dma_resv_assert_held(buf->resv);
-
 	if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
 		return -EINVAL;
 
-- 
2.39.2