On Thu, May 07, 2015 at 06:58:44PM +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 Stanislawski, but this is a simpler way to do it.
v2: move owner to struct dma_buf, and use DEFINE_DMA_BUF_EXPORT_INFO macro to simplify the change.
Signed-off-by: Sumit Semwal sumit.semwal@linaro.org
[1]: https://lkml.org/lkml/2012/8/8/163
drivers/dma-buf/dma-buf.c | 10 +++++++++- include/linux/dma-buf.h | 10 ++++++++-- 2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index c5a9138a6a8d..0eff4bf56ef6 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->owner);
The module can now go away.
mutex_lock(&db_list.lock); list_del(&dmabuf->list_node);
But you reference it here :(
Please drop the reference at the last possible moment.
thanks,
greg k-h