linux-kernel - [PATCH v4 18/21] dma-buf: Move dma_buf_mmap() to dynamic locking specification

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Message-Id: <20220831153757.97381-19-dmitry.osipenko@collabora.com>
Date:   Wed, 31 Aug 2022 18:37:54 +0300
From:   Dmitry Osipenko <dmitry.osipenko@...labora.com>
To:     David Airlie <airlied@...ux.ie>, Gerd Hoffmann <kraxel@...hat.com>,
        Gurchetan Singh <gurchetansingh@...omium.org>,
        Chia-I Wu <olvaffe@...il.com>, Daniel Vetter <daniel@...ll.ch>,
        Daniel Almeida <daniel.almeida@...labora.com>,
        Gert Wollny <gert.wollny@...labora.com>,
        Gustavo Padovan <gustavo.padovan@...labora.com>,
        Daniel Stone <daniel@...ishbar.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Rob Clark <robdclark@...il.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Tomasz Figa <tfiga@...omium.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        Thomas Hellström <thomas_os@...pmail.org>,
        Qiang Yu <yuq825@...il.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Amol Maheshwari <amahesh@....qualcomm.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Tomi Valkeinen <tomba@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Lucas Stach <l.stach@...gutronix.de>,
        Christian Gmeiner <christian.gmeiner@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Dmitry Osipenko <digetx@...il.com>,
        linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org,
        amd-gfx@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        kernel@...labora.com, virtualization@...ts.linux-foundation.org,
        linux-rdma@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: [PATCH v4 18/21] dma-buf: Move dma_buf_mmap() to dynamic locking specification

Move dma_buf_mmap() function to the dynamic locking specification by
taking the reservation lock. Neither of the today's drivers take the
reservation lock within the mmap() callback, hence it's safe to enforce
the locking.

Acked-by: Christian König <christian.koenig@....com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
---
 drivers/dma-buf/dma-buf.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 8e928fe6e8df..d9130486cb8f 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1389,6 +1389,8 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);
 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 		 unsigned long pgoff)
 {
+	int ret;
+
 	if (WARN_ON(!dmabuf || !vma))
 		return -EINVAL;
 
@@ -1409,7 +1411,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	vma_set_file(vma, dmabuf->file);
 	vma->vm_pgoff = pgoff;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	dma_resv_lock(dmabuf->resv, NULL);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+	dma_resv_unlock(dmabuf->resv);
+
+	return ret;
 }
 EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
 
-- 
2.37.2