From: "Christian König" <christian.koenig@amd.com>
To: "Dmitry Osipenko" <dmitry.osipenko@collabora.com>,
"David Airlie" <airlied@linux.ie>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Gurchetan Singh" <gurchetansingh@chromium.org>,
"Chia-I Wu" <olvaffe@gmail.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Daniel Almeida" <daniel.almeida@collabora.com>,
"Gert Wollny" <gert.wollny@collabora.com>,
"Gustavo Padovan" <gustavo.padovan@collabora.com>,
"Daniel Stone" <daniel@fooishbar.org>,
"Tomeu Vizoso" <tomeu.vizoso@collabora.com>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"Rob Clark" <robdclark@gmail.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Pan, Xinhui" <Xinhui.Pan@amd.com>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Tomasz Figa" <tfiga@chromium.org>,
"Marek Szyprowski" <m.szyprowski@samsung.com>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Alex Deucher" <alexander.deucher@amd.com>,
"Jani Nikula" <jani.nikula@linux.intel.com>,
"Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>,
"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
"Tvrtko Ursulin" <tvrtko.ursulin@linux.intel.com>,
"Thomas Hellström" <thomas_os@shipmail.org>,
"Qiang Yu" <yuq825@gmail.com>,
"Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>,
"Amol Maheshwari" <amahesh@qti.qualcomm.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Leon Romanovsky" <leon@kernel.org>,
"Juergen Gross" <jgross@suse.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Oleksandr Tyshchenko" <oleksandr_tyshchenko@epam.com>,
"Tomi Valkeinen" <tomba@kernel.org>,
"Russell King" <linux@armlinux.org.uk>,
"Lucas Stach" <l.stach@pengutronix.de>,
"Christian Gmeiner" <christian.gmeiner@gmail.com>
Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
Dmitry Osipenko <digetx@gmail.com>,
linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
amd-gfx@lists.freedesktop.org, intel-gfx@lists.freedesktop.org,
kernel@collabora.com, virtualization@lists.linux-foundation.org,
linux-rdma@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v4 19/21] dma-buf: Document dynamic locking convention
Date: Thu, 1 Sep 2022 09:16:29 +0200 [thread overview]
Message-ID: <192b9a30-6f15-3702-c679-c3f26b76c9ef@amd.com> (raw)
In-Reply-To: <20220831153757.97381-20-dmitry.osipenko@collabora.com>
Am 31.08.22 um 17:37 schrieb Dmitry Osipenko:
> Add documentation for the dynamic locking convention. The documentation
> tells dma-buf API users when they should take the reservation lock and
> when not.
>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
> ---
> Documentation/driver-api/dma-buf.rst | 6 +++
> drivers/dma-buf/dma-buf.c | 64 ++++++++++++++++++++++++++++
> 2 files changed, 70 insertions(+)
>
> diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst
> index 36a76cbe9095..622b8156d212 100644
> --- a/Documentation/driver-api/dma-buf.rst
> +++ b/Documentation/driver-api/dma-buf.rst
> @@ -119,6 +119,12 @@ DMA Buffer ioctls
>
> .. kernel-doc:: include/uapi/linux/dma-buf.h
>
> +DMA-BUF locking convention
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +.. kernel-doc:: drivers/dma-buf/dma-buf.c
> + :doc: locking convention
> +
> Kernel Functions and Structures Reference
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index d9130486cb8f..97ce884fad76 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -794,6 +794,70 @@ static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,
> return sg_table;
> }
>
> +/**
> + * DOC: locking convention
> + *
> + * In order to avoid deadlock situations between dma-buf exports and importers,
> + * all dma-buf API users must follow the common dma-buf locking convention.
> + *
> + * Convention for importers
> + *
> + * 1. Importers must hold the dma-buf reservation lock when calling these
> + * functions:
> + *
> + * - dma_buf_pin()
> + * - dma_buf_unpin()
> + * - dma_buf_map_attachment()
> + * - dma_buf_unmap_attachment()
> + * - dma_buf_vmap()
> + * - dma_buf_vunmap()
> + *
> + * 2. Importers must not hold the dma-buf reservation lock when calling these
> + * functions:
> + *
> + * - dma_buf_attach()
> + * - dma_buf_dynamic_attach()
> + * - dma_buf_detach()
> + * - dma_buf_export(
> + * - dma_buf_fd()
> + * - dma_buf_get()
> + * - dma_buf_put()
> + * - dma_buf_mmap()
> + * - dma_buf_begin_cpu_access()
> + * - dma_buf_end_cpu_access()
> + * - dma_buf_map_attachment_unlocked()
> + * - dma_buf_unmap_attachment_unlocked()
> + * - dma_buf_vmap_unlocked()
> + * - dma_buf_vunmap_unlocked()
> + *
> + * Convention for exporters
> + *
> + * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf
> + * reservation and exporter can take the lock:
> + *
> + * - &dma_buf_ops.attach()
> + * - &dma_buf_ops.detach()
> + * - &dma_buf_ops.release()
> + * - &dma_buf_ops.begin_cpu_access()
> + * - &dma_buf_ops.end_cpu_access()
> + *
> + * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf
> + * reservation and exporter can't take the lock:
> + *
> + * - &dma_buf_ops.pin()
> + * - &dma_buf_ops.unpin()
> + * - &dma_buf_ops.map_dma_buf()
> + * - &dma_buf_ops.unmap_dma_buf()
> + * - &dma_buf_ops.mmap()
> + * - &dma_buf_ops.vmap()
> + * - &dma_buf_ops.vunmap()
> + *
> + * 3. Exporters must hold the dma-buf reservation lock when calling these
> + * functions:
> + *
> + * - dma_buf_move_notify()
> + */
> +
> /**
> * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
> * @dmabuf: [in] buffer to attach device to.
next prev parent reply other threads:[~2022-09-01 7:16 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-31 15:37 [PATCH v4 00/21] Move all drivers to a common dma-buf locking convention Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 01/21] dma-buf: Add unlocked variant of vmapping functions Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 02/21] dma-buf: Add unlocked variant of attachment-mapping functions Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 03/21] drm/gem: Take reservation lock for vmap/vunmap operations Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 04/21] drm/prime: Prepare to dynamic dma-buf locking specification Dmitry Osipenko
2022-09-01 6:42 ` Christian König
2022-08-31 15:37 ` [PATCH v4 05/21] drm/armada: " Dmitry Osipenko
2022-09-01 6:43 ` Christian König
2022-08-31 15:37 ` [PATCH v4 06/21] drm/i915: " Dmitry Osipenko
2022-09-01 6:45 ` Christian König
2022-09-01 10:44 ` Dmitry Osipenko
2022-09-01 14:02 ` Ruhl, Michael J
2022-09-02 10:31 ` Dmitry Osipenko
2022-09-02 10:38 ` Dmitry Osipenko
2022-09-02 16:26 ` Ruhl, Michael J
2022-09-09 17:36 ` Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 07/21] drm/omapdrm: " Dmitry Osipenko
2022-09-01 6:45 ` [Linaro-mm-sig] " Christian König
2022-08-31 15:37 ` [PATCH v4 08/21] drm/tegra: " Dmitry Osipenko
2022-09-01 6:49 ` Christian König
2022-08-31 15:37 ` [PATCH v4 09/21] drm/etnaviv: " Dmitry Osipenko
2022-09-01 6:50 ` Christian König
2022-09-01 10:41 ` Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 10/21] RDMA/umem: " Dmitry Osipenko
2022-09-01 6:54 ` Christian König
2022-08-31 15:37 ` [PATCH v4 11/21] misc: fastrpc: " Dmitry Osipenko
2022-09-01 6:55 ` Christian König
2022-09-02 9:31 ` Srinivas Kandagatla
2022-09-02 9:31 ` Srinivas Kandagatla
2022-08-31 15:37 ` [PATCH v4 12/21] xen/gntdev: " Dmitry Osipenko
2022-08-31 15:43 ` Juergen Gross
2022-09-01 7:04 ` Christian König
2022-08-31 15:37 ` [PATCH v4 13/21] media: videobuf2: " Dmitry Osipenko
2022-09-01 7:04 ` Christian König
2022-08-31 15:37 ` [PATCH v4 14/21] media: tegra-vde: " Dmitry Osipenko
2022-09-01 7:05 ` Christian König
2022-08-31 15:37 ` [PATCH v4 15/21] dma-buf: Move dma_buf_vmap() to dynamic " Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 16/21] dma-buf: Move dma_buf_attach() " Dmitry Osipenko
2022-09-01 7:07 ` Christian König
2022-08-31 15:37 ` [PATCH v4 17/21] dma-buf: Move dma_buf_map_attachment() " Dmitry Osipenko
2022-09-01 7:08 ` Christian König
2022-08-31 15:37 ` [PATCH v4 18/21] dma-buf: Move dma_buf_mmap() " Dmitry Osipenko
2022-08-31 15:37 ` [PATCH v4 19/21] dma-buf: Document dynamic locking convention Dmitry Osipenko
2022-09-01 7:16 ` Christian König [this message]
2022-08-31 15:37 ` [PATCH v4 20/21] media: videobuf2: Stop using internal dma-buf lock Dmitry Osipenko
2022-09-01 7:46 ` Christian König
2022-08-31 15:37 ` [PATCH v4 21/21] dma-buf: Remove obsoleted internal lock Dmitry Osipenko
2022-09-01 7:46 ` Christian König
2022-09-01 7:49 ` [PATCH v4 00/21] Move all drivers to a common dma-buf locking convention Christian König
2022-09-01 10:47 ` Dmitry Osipenko
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