Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758611Ab2HHNfk (ORCPT ); Wed, 8 Aug 2012 09:35:40 -0400 Received: from perceval.ideasonboard.com ([95.142.166.194]:47155 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758202Ab2HHNfh (ORCPT ); Wed, 8 Aug 2012 09:35:37 -0400 From: Laurent Pinchart To: dri-devel@lists.freedesktop.org Cc: Tomasz Stanislawski , linaro-mm-sig@lists.linaro.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, Pawel Osciak , Greg Kroah-Hartman , Jerome Glisse , Vinod Koul , Kyungmin Park , Rob Landley , Daniel Vetter , Alex Deucher , Rob Clark , Dan Williams , Marek Szyprowski , Sumit Semwal , linux-media@vger.kernel.org Subject: Re: [PATCH] dma-buf: add reference counting for exporter module Date: Wed, 08 Aug 2012 15:35:47 +0200 Message-ID: <1404275.atroogfRqe@avalon> User-Agent: KMail/4.8.3 (Linux/3.3.8-gentoo; KDE/4.8.3; x86_64; ; ) In-Reply-To: <50223CC5.9060007@samsung.com> References: <50223CC5.9060007@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6796 Lines: 175 Hi Tomasz, Thanks for the patch. On Wednesday 08 August 2012 12:17:41 Tomasz Stanislawski wrote: > This patch adds reference counting on a module that exports dma-buf and > implements its operations. This prevents the module from being unloaded > while DMABUF file is in use. > > Signed-off-by: Tomasz Stanislawski > --- > Documentation/dma-buf-sharing.txt | 3 ++- > drivers/base/dma-buf.c | 10 +++++++++- > drivers/gpu/drm/exynos/exynos_drm_dmabuf.c | 1 + > drivers/gpu/drm/i915/i915_gem_dmabuf.c | 1 + > drivers/gpu/drm/nouveau/nouveau_prime.c | 1 + > drivers/gpu/drm/radeon/radeon_prime.c | 1 + > drivers/staging/omapdrm/omap_gem_dmabuf.c | 1 + > include/linux/dma-buf.h | 2 ++ > 8 files changed, 18 insertions(+), 2 deletions(-) > > diff --git a/Documentation/dma-buf-sharing.txt > b/Documentation/dma-buf-sharing.txt index ad86fb8..2613057 100644 > --- a/Documentation/dma-buf-sharing.txt > +++ b/Documentation/dma-buf-sharing.txt > @@ -49,7 +49,8 @@ The dma_buf buffer sharing API usage contains the > following steps: The buffer exporter announces its wish to export a buffer. > In this, it connects its own private buffer data, provides implementation > for operations that can be performed on the exported dma_buf, and flags for > the file > - associated with this buffer. > + associated with this buffer. The operations structure has owner field. > + You should initialize this to THIS_MODULE in most cases. > > Interface: > struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops, > diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c > index c30f3e1..d14b2f5 100644 > --- a/drivers/base/dma-buf.c > +++ b/drivers/base/dma-buf.c > @@ -27,6 +27,7 @@ > #include > #include > #include > +#include > > static inline int is_dma_buf_file(struct file *); > > @@ -40,6 +41,7 @@ static int dma_buf_release(struct inode *inode, struct > file *file) dmabuf = file->private_data; > > dmabuf->ops->release(dmabuf); > + module_put(dmabuf->ops->owner); > kfree(dmabuf); > return 0; > } > @@ -96,6 +98,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct > dma_buf_ops *ops, struct file *file; > > if (WARN_ON(!priv || !ops > + || !ops->owner THIS_MODULE is defined as ((struct module *)0) when the driver is built-in, this check should thus be removed. > || !ops->map_dma_buf > || !ops->unmap_dma_buf > || !ops->release > > @@ -105,9 +108,14 @@ struct dma_buf *dma_buf_export(void *priv, const struct > dma_buf_ops *ops, return ERR_PTR(-EINVAL); > } > > + if (!try_module_get(ops->owner)) > + return ERR_PTR(-ENOENT); > + > dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL); > - if (dmabuf == NULL) > + if (dmabuf == NULL) { > + module_put(ops->owner); > return ERR_PTR(-ENOMEM); > + } > > dmabuf->priv = priv; > dmabuf->ops = ops; > diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c index 613bf8a..cf3bc6d 100644 > --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c > @@ -164,6 +164,7 @@ static void exynos_gem_dmabuf_kunmap(struct dma_buf > *dma_buf, } > > static struct dma_buf_ops exynos_dmabuf_ops = { > + .owner = THIS_MODULE, > .map_dma_buf = exynos_gem_map_dma_buf, > .unmap_dma_buf = exynos_gem_unmap_dma_buf, > .kmap = exynos_gem_dmabuf_kmap, > diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c > b/drivers/gpu/drm/i915/i915_gem_dmabuf.c index aa308e1..07ff03b 100644 > --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c > +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c > @@ -152,6 +152,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf, > struct vm_area_struct * } > > static const struct dma_buf_ops i915_dmabuf_ops = { > + .owner = THIS_MODULE, > .map_dma_buf = i915_gem_map_dma_buf, > .unmap_dma_buf = i915_gem_unmap_dma_buf, > .release = i915_gem_dmabuf_release, > diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c > b/drivers/gpu/drm/nouveau/nouveau_prime.c index a25cf2c..8605033 100644 > --- a/drivers/gpu/drm/nouveau/nouveau_prime.c > +++ b/drivers/gpu/drm/nouveau/nouveau_prime.c > @@ -127,6 +127,7 @@ static void nouveau_gem_prime_vunmap(struct dma_buf > *dma_buf, void *vaddr) } > > static const struct dma_buf_ops nouveau_dmabuf_ops = { > + .owner = THIS_MODULE, > .map_dma_buf = nouveau_gem_map_dma_buf, > .unmap_dma_buf = nouveau_gem_unmap_dma_buf, > .release = nouveau_gem_dmabuf_release, > diff --git a/drivers/gpu/drm/radeon/radeon_prime.c > b/drivers/gpu/drm/radeon/radeon_prime.c index 6bef46a..4061fd3 100644 > --- a/drivers/gpu/drm/radeon/radeon_prime.c > +++ b/drivers/gpu/drm/radeon/radeon_prime.c > @@ -127,6 +127,7 @@ static void radeon_gem_prime_vunmap(struct dma_buf > *dma_buf, void *vaddr) mutex_unlock(&dev->struct_mutex); > } > const static struct dma_buf_ops radeon_dmabuf_ops = { > + .owner = THIS_MODULE, > .map_dma_buf = radeon_gem_map_dma_buf, > .unmap_dma_buf = radeon_gem_unmap_dma_buf, > .release = radeon_gem_dmabuf_release, > diff --git a/drivers/staging/omapdrm/omap_gem_dmabuf.c > b/drivers/staging/omapdrm/omap_gem_dmabuf.c index 42728e0..6a4dd67 100644 > --- a/drivers/staging/omapdrm/omap_gem_dmabuf.c > +++ b/drivers/staging/omapdrm/omap_gem_dmabuf.c > @@ -179,6 +179,7 @@ out_unlock: > } > > struct dma_buf_ops omap_dmabuf_ops = { > + .owner = THIS_MODULE, > .map_dma_buf = omap_gem_map_dma_buf, > .unmap_dma_buf = omap_gem_unmap_dma_buf, > .release = omap_gem_dmabuf_release, > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index eb48f38..22953de 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -37,6 +37,7 @@ struct dma_buf_attachment; > > /** > * struct dma_buf_ops - operations possible on struct dma_buf > + * @owner: the module that implements dma_buf operations > * @attach: [optional] allows different devices to 'attach' themselves to > the * given buffer. It might return -EBUSY to signal that backing > storage * is already allocated and incompatible with the requirements > @@ -70,6 +71,7 @@ struct dma_buf_attachment; > * @vunmap: [optional] unmaps a vmap from the buffer > */ > struct dma_buf_ops { > + struct module *owner; > int (*attach)(struct dma_buf *, struct device *, > struct dma_buf_attachment *); -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/