On 7 May 2015 at 13:40, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> 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.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, > > 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. -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
