Re: [Intel-gfx] [PATCH] dma-buf: add ref counting for module as exporter
On Thu, May 07, 2015 at 01:00:52PM +0530, Sumit Semwal wrote:
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.stanisl...@samsung.com
Acked-by: Daniel Vetter dan...@ffwll.ch
[sumits: updated rebased as per review comments]
Signed-off-by: Sumit Semwal sumit.sem...@linaro.org
[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,
The easier way to do this is change the registration function to add
the module owner automatically, which keeps you from having to modify
all of the individual drivers. Look at how pci and usb do this for
their driver registration functions. That should result in a much
smaller patch, that always works properly for everyone (there's no way
for driver to get it wrong.)
thanks,
greg k-h
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Re: [Intel-gfx] [PATCH] dma-buf: add ref counting for module as exporter
On 7 May 2015 at 13:40, Greg KH gre...@linuxfoundation.org wrote:
On Thu, May 07, 2015 at 01:00:52PM +0530, Sumit Semwal wrote:
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.stanisl...@samsung.com
Acked-by: Daniel Vetter dan...@ffwll.ch
[sumits: updated rebased as per review comments]
Signed-off-by: Sumit Semwal sumit.sem...@linaro.org
[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,
The easier way to do this is change the registration function to add
the module owner automatically, which keeps you from having to modify
all of the individual drivers. Look at how pci and usb do this for
their driver registration functions. That should result in a much
smaller patch, that always works properly for everyone (there's no way
for driver to get it wrong.)
Thanks Greg; but of course, you're right! We already have a
DEFINE_DMA_BUF_EXPORT_INFO macro, so this is far easier incorporated
into that.
I will spin up the (much simpler) patch and repost!
thanks,
greg k-h
Best regards,
Sumit.
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