linux-kernel - [PATCH v1 4/7] Revert "fastrpc: Assert held reservation lock for dma-buf mmapping"

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Date:   Sun,  2 Apr 2023 19:48:23 +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 4/7] Revert "fastrpc: 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: 265751a513ad ("fastrpc: Assert held reservation lock for dma-buf mmapping")
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
 drivers/misc/fastrpc.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index a701132638cf..7e9c9ad37fd9 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -6,7 +6,6 @@
 #include <linux/device.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-mapping.h>
-#include <linux/dma-resv.h>
 #include <linux/idr.h>
 #include <linux/list.h>
 #include <linux/miscdevice.h>
@@ -733,8 +732,6 @@ static int fastrpc_mmap(struct dma_buf *dmabuf,
 	struct fastrpc_buf *buf = dmabuf->priv;
 	size_t size = vma->vm_end - vma->vm_start;
 
-	dma_resv_assert_held(dmabuf->resv);
-
 	return dma_mmap_coherent(buf->dev, vma, buf->virt,
 				 FASTRPC_PHYS(buf->phys), size);
 }
-- 
2.39.2