From: Greg KH <gregkh@linuxfoundation.org>
To: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
linux-arm-kernel@lists.infradead.org,
rmk+kernel@arm.linux.org.uk, airlied@linux.ie, kgene@kernel.org,
thierry.reding@gmail.com, pawel@osciak.com,
m.szyprowski@samsung.com, mchehab@osg.samsung.com,
linaro-kernel@lists.linaro.org, robdclark@gmail.com,
daniel@ffwll.ch
Subject: Re: [PATCH v2] dma-buf: add ref counting for module as exporter
Date: Thu, 7 May 2015 22:49:48 +0200 [thread overview]
Message-ID: <20150507204948.GA28822@kroah.com> (raw)
In-Reply-To: <1431005324-22234-1-git-send-email-sumit.semwal@linaro.org>
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
WARNING: multiple messages have this Message-ID (diff)
From: gregkh@linuxfoundation.org (Greg KH)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] dma-buf: add ref counting for module as exporter
Date: Thu, 7 May 2015 22:49:48 +0200 [thread overview]
Message-ID: <20150507204948.GA28822@kroah.com> (raw)
In-Reply-To: <1431005324-22234-1-git-send-email-sumit.semwal@linaro.org>
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
next prev parent reply other threads:[~2015-05-07 20:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-07 13:28 [PATCH v2] dma-buf: add ref counting for module as exporter Sumit Semwal
2015-05-07 13:28 ` Sumit Semwal
2015-05-07 20:49 ` Greg KH [this message]
2015-05-07 20:49 ` Greg KH
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