[PATCH] dma-buf: add ref counting for module as exporter

From: Sumit Semwal
Date: Thu May 07 2015 - 03:31:23 EST

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Add reference counting on a kernel module that exports dma-buf and
implements its operations. This prevents the module from being unloaded
while DMABUF file is in use.

The original patch [1] was submitted by Tomasz, but he's since shifted
jobs and a ping didn't elicit any response.

[tomasz: Original author]
Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
Acked-by: Daniel Vetter <daniel@xxxxxxxx>
[sumits: updated & rebased as per review comments]
Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>

[1]: https://lkml.org/lkml/2012/8/8/163
---
drivers/dma-buf/dma-buf.c | 9 ++++++++-
drivers/gpu/drm/armada/armada_gem.c | 1 +
drivers/gpu/drm/drm_prime.c | 1 +
drivers/gpu/drm/exynos/exynos_drm_dmabuf.c | 1 +
drivers/gpu/drm/i915/i915_gem_dmabuf.c | 1 +
drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 1 +
drivers/gpu/drm/tegra/gem.c | 1 +
drivers/gpu/drm/udl/udl_dmabuf.c | 1 +
drivers/gpu/drm/vmwgfx/vmwgfx_prime.c | 1 +
drivers/media/v4l2-core/videobuf2-dma-contig.c | 1 +
drivers/media/v4l2-core/videobuf2-dma-sg.c | 1 +
drivers/media/v4l2-core/videobuf2-vmalloc.c | 1 +
drivers/staging/android/ion/ion.c | 1 +
include/linux/dma-buf.h | 2 ++
14 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index c5a9138a6a8d..9583eac0238f 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -29,6 +29,7 @@
#include <linux/anon_inodes.h>
#include <linux/export.h>
#include <linux/debugfs.h>
+#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/reservation.h>
@@ -64,6 +65,7 @@ static int dma_buf_release(struct inode *inode, struct file *file)
BUG_ON(dmabuf->cb_shared.active || dmabuf->cb_excl.active);

dmabuf->ops->release(dmabuf);
+ module_put(dmabuf->ops->owner);

mutex_lock(&db_list.lock);
list_del(&dmabuf->list_node);
@@ -302,9 +304,14 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
return ERR_PTR(-EINVAL);
}

+ if (!try_module_get(exp_info->ops->owner))
+ return ERR_PTR(-ENOENT);
+
dmabuf = kzalloc(alloc_size, GFP_KERNEL);
- if (dmabuf == NULL)
+ if (!dmabuf) {
+ module_put(exp_info->ops->owner);
return ERR_PTR(-ENOMEM);
+ }

dmabuf->priv = exp_info->priv;
dmabuf->ops = exp_info->ops;
diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c
index 580e10acaa3a..d2c5fc1269b7 100644
--- a/drivers/gpu/drm/armada/armada_gem.c
+++ b/drivers/gpu/drm/armada/armada_gem.c
@@ -524,6 +524,7 @@ armada_gem_dmabuf_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
}

static const struct dma_buf_ops armada_gem_prime_dmabuf_ops = {
+ .owner = THIS_MODULE,
.map_dma_buf = armada_gem_prime_map_dma_buf,
.unmap_dma_buf = armada_gem_prime_unmap_dma_buf,
.release = drm_gem_dmabuf_release,
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 7fec191b45f7..ed4a6e35dd91 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -289,6 +289,7 @@ static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
}

static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = drm_gem_map_attach,
.detach = drm_gem_map_detach,
.map_dma_buf = drm_gem_map_dma_buf,
diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
index cd485c091b30..35fa029353e9 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
@@ -169,6 +169,7 @@ static int exynos_gem_dmabuf_mmap(struct dma_buf *dma_buf,
}

static struct dma_buf_ops exynos_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = exynos_gem_attach_dma_buf,
.detach = exynos_gem_detach_dma_buf,
.map_dma_buf = exynos_gem_map_dma_buf,
diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
index 7998da27c500..b9355d8d4862 100644
--- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
@@ -213,6 +213,7 @@ static int i915_gem_begin_cpu_access(struct dma_buf *dma_buf, size_t start, size
}

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 = drm_gem_dmabuf_release,
diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
index 344fd789170d..977ece9be62c 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c
@@ -156,6 +156,7 @@ static int omap_gem_dmabuf_mmap(struct dma_buf *buffer,
}

static 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/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
index 1217272a51f2..7af37a445524 100644
--- a/drivers/gpu/drm/tegra/gem.c
+++ b/drivers/gpu/drm/tegra/gem.c
@@ -611,6 +611,7 @@ static void tegra_gem_prime_vunmap(struct dma_buf *buf, void *vaddr)
}

static const struct dma_buf_ops tegra_gem_prime_dmabuf_ops = {
+ .owner = THIS_MODULE,
.map_dma_buf = tegra_gem_prime_map_dma_buf,
.unmap_dma_buf = tegra_gem_prime_unmap_dma_buf,
.release = tegra_gem_prime_release,
diff --git a/drivers/gpu/drm/udl/udl_dmabuf.c b/drivers/gpu/drm/udl/udl_dmabuf.c
index e2243edd1ce3..b67bd66c4636 100644
--- a/drivers/gpu/drm/udl/udl_dmabuf.c
+++ b/drivers/gpu/drm/udl/udl_dmabuf.c
@@ -187,6 +187,7 @@ static int udl_dmabuf_mmap(struct dma_buf *dma_buf,
}

static struct dma_buf_ops udl_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = udl_attach_dma_buf,
.detach = udl_detach_dma_buf,
.map_dma_buf = udl_map_dma_buf,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c b/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
index 31fe32d8d65a..81aa6eae9031 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_prime.c
@@ -103,6 +103,7 @@ static int vmw_prime_dmabuf_mmap(struct dma_buf *dma_buf,
}

const struct dma_buf_ops vmw_prime_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = vmw_prime_map_attach,
.detach = vmw_prime_map_detach,
.map_dma_buf = vmw_prime_map_dma_buf,
diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index 644dec73d220..22cb21480fb8 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -365,6 +365,7 @@ static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
}

static struct dma_buf_ops vb2_dc_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = vb2_dc_dmabuf_ops_attach,
.detach = vb2_dc_dmabuf_ops_detach,
.map_dma_buf = vb2_dc_dmabuf_ops_map,
diff --git a/drivers/media/v4l2-core/videobuf2-dma-sg.c b/drivers/media/v4l2-core/videobuf2-dma-sg.c
index 45c708e463b9..f659ee409148 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-sg.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-sg.c
@@ -568,6 +568,7 @@ static int vb2_dma_sg_dmabuf_ops_mmap(struct dma_buf *dbuf,
}

static struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = vb2_dma_sg_dmabuf_ops_attach,
.detach = vb2_dma_sg_dmabuf_ops_detach,
.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
diff --git a/drivers/media/v4l2-core/videobuf2-vmalloc.c b/drivers/media/v4l2-core/videobuf2-vmalloc.c
index 657ab302a5cf..a76ce4d989c8 100644
--- a/drivers/media/v4l2-core/videobuf2-vmalloc.c
+++ b/drivers/media/v4l2-core/videobuf2-vmalloc.c
@@ -353,6 +353,7 @@ static int vb2_vmalloc_dmabuf_ops_mmap(struct dma_buf *dbuf,
}

static struct dma_buf_ops vb2_vmalloc_dmabuf_ops = {
+ .owner = THIS_MODULE,
.attach = vb2_vmalloc_dmabuf_ops_attach,
.detach = vb2_vmalloc_dmabuf_ops_detach,
.map_dma_buf = vb2_vmalloc_dmabuf_ops_map,
diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index b0b96ab31954..5af1355c874c 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -1088,6 +1088,7 @@ static void ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf, size_t start,
}

static struct dma_buf_ops dma_buf_ops = {
+ .owner = THIS_MODULE,
.map_dma_buf = ion_map_dma_buf,
.unmap_dma_buf = ion_unmap_dma_buf,
.mmap = ion_mmap,
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 2f0b431b73e0..22d367080943 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -39,6 +39,7 @@ 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
@@ -72,6 +73,7 @@ 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 *);

--
1.9.1

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Next message: Christoph Hellwig: "Re: [PATCH] remove <asm/scatterlist.h>"
Previous message: Christoph Hellwig: "Re: [Linux-nvdimm] [PATCH v2 00/20] libnd: non-volatile memory device support"
Next in thread: Greg KH: "Re: [PATCH] dma-buf: add ref counting for module as exporter"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]