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Message-ID: <CAO_48GGxF0x7LKdQ+Az6YbY9uy394croggbPVfhPqQJ+paXAXg@mail.gmail.com>
Date: Tue, 20 Sep 2022 19:46:46 +0530
From: Sumit Semwal <sumit.semwal@...aro.org>
To: Dmitry Osipenko <dmitry.osipenko@...labora.com>
Cc: 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>,
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>,
Ruhl Michael J <michael.j.ruhl@...el.com>,
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: Re: [PATCH v5 00/21] Move all drivers to a common dma-buf locking convention
Hi Dmitry,
On Wed, 14 Sept 2022 at 00:58, Dmitry Osipenko
<dmitry.osipenko@...labora.com> wrote:
>
> Hello,
>
> This series moves all drivers to a dynamic dma-buf locking specification.
> From now on all dma-buf importers are made responsible for holding
> dma-buf's reservation lock around all operations performed over dma-bufs
> in accordance to the locking specification. This allows us to utilize
> reservation lock more broadly around kernel without fearing of a potential
> deadlocks.
Thank you for the excellent work on this series - apart from a minor
nit in patch 15, please feel free to add my:
Acked-by: Sumit Semwal <sumit.semwal@...aro.org>
for the relevant dma-buf patches (1, 2, 15-19, 21).
Best regards,
Sumit.
>
> This patchset passes all i915 selftests. It was also tested using VirtIO,
> Panfrost, Lima, Tegra, udmabuf, AMDGPU and Nouveau drivers. I tested cases
> of display+GPU, display+V4L and GPU+V4L dma-buf sharing (where appropriate),
> which covers majority of kernel drivers since rest of the drivers share
> same or similar code paths.
>
> Changelog:
>
> v5: - Added acks and r-bs that were given to v4.
>
> - Changed i915 preparation patch like was suggested by Michael Ruhl.
> The scope of reservation locking is smaller now.
>
> v4: - Added dma_buf_mmap() to the "locking convention" documentation,
> which was missed by accident in v3.
>
> - Added acks from Christian König, Tomasz Figa and Hans Verkuil that
> they gave to couple v3 patches.
>
> - Dropped the "_unlocked" postfix from function names that don't have
> the locked variant, as was requested by Christian König.
>
> - Factored out the per-driver preparations into separate patches
> to ease reviewing of the changes, which is now doable without the
> global dma-buf functions renaming.
>
> - Factored out the dynamic locking convention enforcements into separate
> patches which add the final dma_resv_assert_held(dmabuf->resv) to the
> dma-buf API functions.
>
> v3: - Factored out dma_buf_mmap_unlocked() and attachment functions
> into aseparate patches, like was suggested by Christian König.
>
> - Corrected and factored out dma-buf locking documentation into
> a separate patch, like was suggested by Christian König.
>
> - Intel driver dropped the reservation locking fews days ago from
> its BO-release code path, but we need that locking for the imported
> GEMs because in the end that code path unmaps the imported GEM.
> So I added back the locking needed by the imported GEMs, updating
> the "dma-buf attachment locking specification" patch appropriately.
>
> - Tested Nouveau+Intel dma-buf import/export combo.
>
> - Tested udmabuf import to i915/Nouveau/AMDGPU.
>
> - Fixed few places in Etnaviv, Panfrost and Lima drivers that I missed
> to switch to locked dma-buf vmapping in the drm/gem: Take reservation
> lock for vmap/vunmap operations" patch. In a result invalidated the
> Christian's r-b that he gave to v2.
>
> - Added locked dma-buf vmap/vunmap functions that are needed for fixing
> vmappping of Etnaviv, Panfrost and Lima drivers mentioned above.
> I actually had this change stashed for the drm-shmem shrinker patchset,
> but then realized that it's already needed by the dma-buf patches.
> Also improved my tests to better cover these code paths.
>
> v2: - Changed locking specification to avoid problems with a cross-driver
> ww locking, like was suggested by Christian König. Now the attach/detach
> callbacks are invoked without the held lock and exporter should take the
> lock.
>
> - Added "locking convention" documentation that explains which dma-buf
> functions and callbacks are locked/unlocked for importers and exporters,
> which was requested by Christian König.
>
> - Added ack from Tomasz Figa to the V4L patches that he gave to v1.
>
> Dmitry Osipenko (21):
> dma-buf: Add unlocked variant of vmapping functions
> dma-buf: Add unlocked variant of attachment-mapping functions
> drm/gem: Take reservation lock for vmap/vunmap operations
> drm/prime: Prepare to dynamic dma-buf locking specification
> drm/armada: Prepare to dynamic dma-buf locking specification
> drm/i915: Prepare to dynamic dma-buf locking specification
> drm/omapdrm: Prepare to dynamic dma-buf locking specification
> drm/tegra: Prepare to dynamic dma-buf locking specification
> drm/etnaviv: Prepare to dynamic dma-buf locking specification
> RDMA/umem: Prepare to dynamic dma-buf locking specification
> misc: fastrpc: Prepare to dynamic dma-buf locking specification
> xen/gntdev: Prepare to dynamic dma-buf locking specification
> media: videobuf2: Prepare to dynamic dma-buf locking specification
> media: tegra-vde: Prepare to dynamic dma-buf locking specification
> dma-buf: Move dma_buf_vmap() to dynamic locking specification
> dma-buf: Move dma_buf_attach() to dynamic locking specification
> dma-buf: Move dma_buf_map_attachment() to dynamic locking
> specification
> dma-buf: Move dma_buf_mmap() to dynamic locking specification
> dma-buf: Document dynamic locking convention
> media: videobuf2: Stop using internal dma-buf lock
> dma-buf: Remove obsoleted internal lock
>
> Documentation/driver-api/dma-buf.rst | 6 +
> drivers/dma-buf/dma-buf.c | 211 +++++++++++++++---
> drivers/gpu/drm/armada/armada_gem.c | 8 +-
> drivers/gpu/drm/drm_client.c | 4 +-
> drivers/gpu/drm/drm_gem.c | 24 ++
> drivers/gpu/drm/drm_gem_dma_helper.c | 6 +-
> drivers/gpu/drm/drm_gem_framebuffer_helper.c | 6 +-
> drivers/gpu/drm/drm_gem_ttm_helper.c | 9 +-
> drivers/gpu/drm/drm_prime.c | 6 +-
> drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 2 +-
> drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 +-
> drivers/gpu/drm/i915/gem/i915_gem_object.c | 14 ++
> .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 16 +-
> drivers/gpu/drm/lima/lima_sched.c | 4 +-
> drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 4 +-
> drivers/gpu/drm/panfrost/panfrost_dump.c | 4 +-
> drivers/gpu/drm/panfrost/panfrost_perfcnt.c | 6 +-
> drivers/gpu/drm/qxl/qxl_object.c | 17 +-
> drivers/gpu/drm/qxl/qxl_prime.c | 4 +-
> drivers/gpu/drm/tegra/gem.c | 17 +-
> drivers/infiniband/core/umem_dmabuf.c | 7 +-
> .../common/videobuf2/videobuf2-dma-contig.c | 22 +-
> .../media/common/videobuf2/videobuf2-dma-sg.c | 19 +-
> .../common/videobuf2/videobuf2-vmalloc.c | 17 +-
> .../platform/nvidia/tegra-vde/dmabuf-cache.c | 6 +-
> drivers/misc/fastrpc.c | 6 +-
> drivers/xen/gntdev-dmabuf.c | 8 +-
> include/drm/drm_gem.h | 3 +
> include/linux/dma-buf.h | 17 +-
> 29 files changed, 320 insertions(+), 155 deletions(-)
>
> --
> 2.37.3
>
--
Thanks and regards,
Sumit Semwal (he / him)
Tech Lead - LCG, Vertical Technologies
Linaro.org │ Open source software for ARM SoCs
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