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Date: Thu, 1 Sep 2022 09:46:59 +0200
From: Christian König <christian.koenig@....com>
To: Dmitry Osipenko <dmitry.osipenko@...labora.com>,
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>,
"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: Re: [PATCH v4 21/21] dma-buf: Remove obsoleted internal lock
Am 31.08.22 um 17:37 schrieb Dmitry Osipenko:
> The internal dma-buf lock isn't needed anymore because the updated
> locking specification claims that dma-buf reservation must be locked
> by importers, and thus, the internal data is already protected by the
> reservation lock. Remove the obsoleted internal lock.
>
> Acked-by: Christian König <christian.koenig@....com>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@...labora.com>
Reviewed-by: Christian König <christian.koenig@....com>
> ---
> drivers/dma-buf/dma-buf.c | 14 ++++----------
> include/linux/dma-buf.h | 9 ---------
> 2 files changed, 4 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 97ce884fad76..772fdd9eeed8 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -656,7 +656,6 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>
> dmabuf->file = file;
>
> - mutex_init(&dmabuf->lock);
> INIT_LIST_HEAD(&dmabuf->attachments);
>
> mutex_lock(&db_list.lock);
> @@ -1502,7 +1501,7 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);
> int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
> {
> struct iosys_map ptr;
> - int ret = 0;
> + int ret;
>
> iosys_map_clear(map);
>
> @@ -1514,28 +1513,25 @@ int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
> if (!dmabuf->ops->vmap)
> return -EINVAL;
>
> - mutex_lock(&dmabuf->lock);
> if (dmabuf->vmapping_counter) {
> dmabuf->vmapping_counter++;
> BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
> *map = dmabuf->vmap_ptr;
> - goto out_unlock;
> + return 0;
> }
>
> BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
>
> ret = dmabuf->ops->vmap(dmabuf, &ptr);
> if (WARN_ON_ONCE(ret))
> - goto out_unlock;
> + return ret;
>
> dmabuf->vmap_ptr = ptr;
> dmabuf->vmapping_counter = 1;
>
> *map = dmabuf->vmap_ptr;
>
> -out_unlock:
> - mutex_unlock(&dmabuf->lock);
> - return ret;
> + return 0;
> }
> EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);
>
> @@ -1577,13 +1573,11 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
> BUG_ON(dmabuf->vmapping_counter == 0);
> BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
>
> - mutex_lock(&dmabuf->lock);
> if (--dmabuf->vmapping_counter == 0) {
> if (dmabuf->ops->vunmap)
> dmabuf->ops->vunmap(dmabuf, map);
> iosys_map_clear(&dmabuf->vmap_ptr);
> }
> - mutex_unlock(&dmabuf->lock);
> }
> EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);
>
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index f11b5bbc2f37..6fa8d4e29719 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -326,15 +326,6 @@ struct dma_buf {
> /** @ops: dma_buf_ops associated with this buffer object. */
> const struct dma_buf_ops *ops;
>
> - /**
> - * @lock:
> - *
> - * Used internally to serialize list manipulation, attach/detach and
> - * vmap/unmap. Note that in many cases this is superseeded by
> - * dma_resv_lock() on @resv.
> - */
> - struct mutex lock;
> -
> /**
> * @vmapping_counter:
> *
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